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29f0111d84147e58240778a1ea211be379d7f337
subsection
14
144
The moduli space of matroids
Then by the definition of the pullback of a matroid bundle, we have (\circ )^\ast ({\mathcal {M}}_\textup {univ})=^\ast (^\ast ({\mathcal {M}}_\textup {univ})), which establishes the functoriality of the bijection \Phi . This completes the proof of the theorem.
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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4d066930b84ac2745266650d95fd5d7eccf1b0f6
subsection
15
144
Duality
One of the fundamental features of matroid theory is that every matroid (with coefficients) comes with a canonical dual matroid. This extends to matroid bundles, and, in fact, the duality is derived from a duality between the moduli spaces.Theorem 1.4 Let E be a non-empty finite ordered set, r\leqslant \#E a natural n...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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5a52ebb4f51b4f50ae8afafd4ed442433e958326
subsection
16
144
Duality
Then the Plücker relation given by an (r-1)-subset I and an (r+1)-subset J of E is0 \quad \leqslant \quad \sum _{i\in J-I} \ ^{(i,I)+(i,J)} \ \cdot \ x_{I\cup \lbrace i\rbrace } \ \cdot \ x_{J-\lbrace i\rbrace }.Note that(I\cup \lbrace i\rbrace )^c=I^c-\lbrace i\rbrace , \quad (J-\lbrace i\rbrace )^c=J^c\cup \lbrace i\...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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2e0bbf8530e7ba8c40445eb3edc8bb98e38a69ec
subsection
17
144
Duality
The dual of \Delta with respect to is the function\textstyle \begin{array}{cccc} \Delta _^{\mbox{[-8]$\vee $}}: & \binom{E}{r^{\mbox{[-8]$\vee $}}} & \longrightarrow & \Gamma (X,{\mathcal {L}}) \\ & I & \longmapsto & _{\mathcal {L}}^\#\circ \Delta (I^c) \end{array}where _{\mathcal {L}}^\#:\Gamma (X,{\mathcal {L}}) \rig...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.aim.2018.12.004", "end": 1067, "openalex_id": "https://openalex.org/W2962744969", "raw": "Matthew Baker and Nathan Bowler. Matroids over partial hyperstructures. Preprint, arXiv:1709.09707, 2017.", "source_ref_id": "c29f3f46...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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b5df5e64456bce28f9b795535a407c71de0af7f1
subsection
18
144
Duality
Then the dual \Delta _^{\mbox{[-8]$\vee $}} of \Delta with respect to is a Grassmann-Plücker function and {\mathcal {M}}_^{\mbox{[-8]$\vee $}} is the matroid bundle on X whose characteristic morphism is_{{\mathcal {M}}_^{\mbox{[-8]$\vee $}}} \ = \ ^{\mbox{[-8]$\vee $}}\circ _{\mathcal {M}}\circ : \ X \ \stackrel{}{\lon...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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658f2765bc6cf313c72b4f9b4dd5c99f66bf2925
subsection
19
144
Duality
The partial order \leqslant is the smallest additive and multiplicative partial order that contains the partial order of \Gamma (X,{\mathcal {L}}^{\otimes i})^+ for every i\geqslant 0.Since \Delta is a Grassmann-Plücker function, the association x_I\mapsto \Delta (I) defines a morphism\textstyle _\Delta : \ {\mathbb {F...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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d60d321adb6eedcbb7070a3b08ed8b890accc03b
subsection
20
144
Duality
This means that we obtain a commutative diagram\textstyle {tikz/fig11} \begin{}[row sep=0pt, column sep=50pt] & \binom{E}{r} {dl}[swap]{j_{r,E}}{rrd}{\Delta } \\ {\mathbb {F}}_1^\pm \big [ \, x_I \, \big | \, I\in \binom{E}{r} \, \big ]\!\sslash \!\operatorname{{Pl}}(r,E) {ddd}[swap]{^{\mbox{[-8]$\vee $}}} {rrr}[swap]{...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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b38a1636913517435dd89c1778bd5477667e9023
subsection
21
144
Rational point sets
In this section, we explain how the matroid space recovers classical objects like the Grassmannian, the Dressian and the MacPhersonian as rational point sets.Let B be a pasteurized ordered blueprint. By the universal property of the matroid space, \operatorname{Mat}(r,E)(B) corresponds to the set of B-matroids of rank ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.jnt.2015.07.015", "end": 615, "openalex_id": "https://openalex.org/W1592683509", "raw": "Oliver Lorscheid and Cecília Salgado. A remark on topologies for rational point sets. J. Number Theory, 159:193–201, 2016.", "source_re...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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d41bc5975c9ffcf8b977ccc7738a25807ccb503f
subsection
22
144
Rational point sets
It turns out that a topological hyperfield is the same as a topological pasture if identified with the associated pasture via the functor (-)^\textup {oblpr}:\operatorname{{HypFields}}\rightarrow \operatorname{{OBlpr}}^\pm . In the following, we consider the following topological pastures:the reals {\mathbb {R}} with t...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.aim.2018.10.021", "end": 1227, "openalex_id": "https://openalex.org/W2899374813", "raw": "Laura Anderson and James F. Davis. Hyperfield Grassmannians. Preprint, arXiv:arXiv:1710.00016, 2017.", "source_ref_id": "53291b94c35cd...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.026975205168128014, -0.01061156950891018, -0.014166560024023056, 0.05520152300596237, -0.037899553775787354, -0.07421232759952545, 0.01815638691186905, 0.02047552354633808, -0.014799744822084904, 0.026517480611801147, -0.044643353670835495, 0.004470438230782747, 0.0067018428817391396, 0...
7993aa64adfc6bbf5e31d06703a59fc60a347845
subsection
23
144
Matroids
A matroid is the same as a {\mathbb {K}}-matroid where {\mathbb {K}}=\lbrace 0,1\rbrace \!\sslash \!\langle 0\leqslant 1+1,0\leqslant 1+1+1 \rangle is the Krasner hyperfield. Thus \operatorname{Mat}(r,E)({\mathbb {K}}) is the set of all matroids of rank r on E. The topology on {\mathbb {K}} turns \operatorname{Mat}(r,E...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.aim.2018.10.021", "end": 394, "openalex_id": "https://openalex.org/W2899374813", "raw": "Laura Anderson and James F. Davis. Hyperfield Grassmannians. Preprint, arXiv:arXiv:1710.00016, 2017.", "source_ref_id": "53291b94c35cd0...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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af7059436056433868fa4790ab5b0767753a7bbd
subsection
24
144
Oriented matroids and the MacPhersonian
Note that as a pasture, the sign hyperfield turns into {\mathbb {S}}=\lbrace 0,1,\rbrace \!\sslash \!{\mathcal {R}} where {\mathcal {R}} is generated by relations 0\leqslant 1+\cdots +1++\cdots + that contain at least one 1 and one .An oriented matroid is the same thing as a {\mathbb {S}}-matroid. Thus \operatorname{Ma...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.aim.2018.10.021", "end": 598, "openalex_id": "https://openalex.org/W2899374813", "raw": "Laura Anderson and James F. Davis. Hyperfield Grassmannians. Preprint, arXiv:arXiv:1710.00016, 2017.", "source_ref_id": "53291b94c35cd0...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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32ae49eaf0335bb8bea30e8a1d7a4a2d80762f15
subsection
25
144
Subvector spaces and the Grassmannian
Let k be a field, which we identify with the pasture k^\bullet \!\sslash \!\langle 0\leqslant \sum a_i|\sum a_i=0\text{ in }k \rangle . (Note that this results from considering k as a partial field and applying the functor \operatorname{{PartFields}}\rightarrow \operatorname{{OBlpr}}^\pm or, equivalently, from consider...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.042307913303375244, -0.022649690508842468, -0.038217537105083466, -0.009813847951591015, -0.04267421364784241, -0.015300750732421875, 0.04441415145993233, -0.012316913343966007, -0.004109453409910202, 0.05323592945933342, -0.0543958880007267, 0.009653590619564056, 0.002117685042321682, ...
6b866d594a7379213b3f8af5d5cb6e92a5251b84
subsection
26
144
The oriented matroid of real subvector spaces
The topology of {\mathbb {R}} endows \operatorname{Mat}(r,E)({\mathbb {R}}) with a topology that coincides with the usual topology of the real Grassmannian. The hyperfield morphism \textup {sign}:{\mathbb {R}}\rightarrow {\mathbb {S}} is continuous and therefore induces a continuous map\operatorname{Gr}(r,E)({\mathbb {...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1007/bf02573979", "end": 1035, "openalex_id": "https://openalex.org/W2103843044", "raw": "Nicolai E. Mnëv and Günter M. Ziegler. Combinatorial models for the finite-dimensional Grassmannians. Discrete Comput. Geom., 10(3):241–250, 1993."...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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38d784f42d718a273ba986fc884f570424ed4b6e
subsection
27
144
Valuated matroids and the Dressian
A valuated matroid is the same thing as a -matroid, where is the tropical hyperfield. Thus \operatorname{Mat}(r,E)( is the set of all valuated matroids of rank r on E. An r-dimensional tropical linear space in {\mathbb {R}}^E is the geometric realization of a valuated matroid as a subspace of {\mathbb {R}}^E, analogous...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1137/080716219", "end": 385, "openalex_id": "https://openalex.org/W2033172904", "raw": "David E. Speyer. Tropical linear spaces. SIAM J. Discrete Math., 22(4):1527–1558, 2008.", "source_ref_id": "77103d13a16a80a791453554528814525ee...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.012567974627017975, -0.05695650354027748, -0.031652677804231644, 0.015177718363702297, 0.001392626203596592, -0.01857343688607216, 0.007226394489407539, 0.028966626152396202, -0.0004299494903534651, 0.04779950901865959, -0.01816137135028839, -0.01455962099134922, -0.008935700170695782, ...
591677cdf444912eb81b1ff3d2ab4a9c50e3867b
subsection
28
144
Regular matroids
It follows from our explanations in section that the subset of regular matroids in \operatorname{Mat}(r,E)({\mathbb {K}}) is equal to the image of the map \operatorname{Mat}(r,E)({\mathbb {F}}_1^\pm )\rightarrow \operatorname{Mat}(r,E)({\mathbb {K}}) induced by the unique morphism {\mathbb {F}}_1^\pm \rightarrow {\math...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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5ce81bb36ffd13f424da463d10922dc2d0007c1e
subsection
29
144
Realization spaces and the Tutte group
A new feature that comes along with the matroid space is the universal pasture associated with a matroid. We will introduce this notion and explain how it interacts with questions about the representability of matroids and realization spaces. We will also discuss the analogous invariant for weak matroids and its relati...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.012360017746686935, 0.007995863445103168, -0.0300607830286026, 0.017105653882026672, -0.02786344662308693, -0.06222734972834587, 0.01007112581282854, 0.05536067113280296, 0.02031010389328003, 0.08423123508691788, -0.01088749710470438, -0.0031395971309393644, 0.011764905415475368, 0.0472...
d91004f238b18ea892702fb2f64f800830105059
subsection
30
144
The universal pasture of a matroid
We can associate with every matroid its universal pasture, which is derived from a certain residue field of the matroid space. We will define the universal pasture and describe its basic properties in this section.Let N=\#\binom{E}{r}-1. Recall from section REF that the matroid space comes with a closed immersion: \ \o...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.004127637483179569, -0.021225670352578163, -0.03183087706565857, 0.0010185574647039175, -0.01225320901721716, -0.04278704524040222, 0.0257729385048151, -0.00343715469352901, 0.01148261409252882, 0.06537079066038132, -0.03228865563869476, 0.0022469302639365196, -0.016434254124760628, -0....
89a372d72c40699c7b5017f7a3638c65f3e4e0c8
subsection
31
144
The universal pasture of a matroid
The stalk at {\mathfrak {p}}_{\mathcal {I}} is the ordered blueprint\textstyle {\mathcal {O}}_{\operatorname{Mat}(r,E),{\mathfrak {p}}_{\mathcal {I}}} \ = \ \big ({\mathbb {F}}_1^\pm \big [ \, x_I^\pm , x_J \, \big | \, I\in {\mathcal {I}},J\in {\mathcal {I}}^c \, \big ]\!\sslash \!\operatorname{{Pl}}(r,E)\big )_0where...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1492, "openalex_id": "", "raw": "Oliver Lorscheid. Blueprints and tropical scheme theory. Lecture notes, http://lorschei.impa.br/2018-Blueprints/versions/lecturenotes180521.pdf, version from May 21, 2018.", "source_ref_id": ...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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45a04f4303e3041080c5bb343445d80cec8fb7f1
subsection
32
144
The universal pasture of a matroid
The support of M is the image point x_M of _M and the universal pasture of M is k_M=k(x_M)^\pm .More explicitly, we have\textstyle k_M \ = \ \big ({\mathbb {F}}_1^\pm \big [ \, x_I^\pm \, \big | \, I\in {\mathcal {I}}\, \big ]\!\sslash \!\operatorname{{Pl}}(r,E)\big )_0^\pmwhere \operatorname{{Pl}}(r,E) is generated by...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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2a8b32ff609017479a4cea16307308b9f6a47b42
subsection
33
144
The universal pasture of a matroid
This means that factors into a uniquely determined morphism \operatorname{Spec}{\mathbb {K}}\rightarrow \operatorname{Spec}k(x) followed by \operatorname{Spec}k(x)\rightarrow \operatorname{Mat}(r,E). This yields a morphism k(x)\rightarrow {\mathbb {K}}, which extends uniquely to a morphism k(x)^\pm \rightarrow {\mathbb...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
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d579c98ad9b7ddc419214a2806afcc431958cc51
subsection
34
144
The universal pasture of a matroid
Thus the morphism resulting from t_M^\ast with the canonical morphism \operatorname{Spec}k_M\rightarrow \operatorname{Mat}(r,E) must be equal to _M.Remark 2.6 As a consequence of Proposition REF and Corollary REF , we see that only the points x in the image of \Phi are supports of matroids.Lemma 2.7 Let k be a field a...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.0073420265689492226, -0.0011318163014948368, -0.054006803780794144, -0.024379342794418335, -0.02361653372645378, -0.051779404282569885, 0.028132358565926552, 0.032404083758592606, 0.01757509633898735, 0.030741160735487938, -0.03722503036260605, -0.04793485254049301, 0.014279765076935291, ...
3935c51f3369f2d9f0069fe0cb948dd17444a3c7
subsection
35
144
The universal pasture of a matroid
By Lemma REF , this is equivalent to k(x)^\times =\lbrace 1,\rbrace , or k(x)={\mathbb {F}}_1^\pm , as claimed. Since {\mathbb {F}}_1^\pm is pasteurized and nonzero, Proposition REF implies that x is the support of a matroid.Example 2.10 (Support of the uniform matroid) The uniform matroid of rank r on E is the matroi...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.017990389838814735, -0.02655070088803768, -0.04531930014491081, -0.02232395112514496, -0.009605555795133114, -0.04357977211475372, 0.04913405701518059, 0.02027924172580242, 0.024872208014130592, 0.03595025837421417, -0.03427176550030708, -0.02229343354701996, 0.027176320552825928, 0.029...
71078d433251e749fef46b111055245e84d252a0
subsection
36
144
The universal pasture of a matroid
Since the Plücker relations in the definition of \operatorname{Mat}(r,E) are merely inequalities, they do not identify any elements of the underlying monoid of {\mathbb {F}}_1^\pm \big [x_I \; \big | \; I\in \binom{E}{r}\big ]. As a result, the underlying topological space of \operatorname{Mat}(r,E) is the same as that...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.006928916089236736, -0.012613984756171703, -0.05158532038331032, -0.010805445723235607, 0.001000610296614468, -0.0009777173399925232, 0.006848790682852268, 0.018634814769029617, 0.0013153875479474664, 0.02214505895972252, -0.0365065336227417, -0.007390589453279972, -0.025640040636062622, ...
4a6a43071ea4b7a70b43d4302c47f822f50a4578
subsection
37
144
The universal pasture of a matroid
The residue field at {\mathfrak {p}}_{\mathcal {I}} is\textstyle k({\mathfrak {p}}_{\mathcal {I}}) \ = \ {\mathcal {O}}_{\operatorname{Mat}(r,E),{\mathfrak {p}}_{\mathcal {I}}}\!\sslash \!\langle x_Jx_I^{-1}\equiv 0 \; | \; J\in {\mathcal {I}}^c \ranglewhere I\in {\mathcal {I}} is an arbitrary fixed index that allows u...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 762, "openalex_id": "", "raw": "Oliver Lorscheid. Blueprints and tropical scheme theory. Lecture notes, http://lorschei.impa.br/2018-Blueprints/versions/lecturenotes180521.pdf, version from May 21, 2018.", "source_ref_id": "...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.03183572739362717, -0.010889161378145218, -0.04172525182366371, -0.04431972652673721, -0.019916405901312828, -0.021228903904557228, 0.040351707488298416, 0.03510171175003052, -0.003155338577926159, 0.04642582684755325, -0.026600992307066917, -0.005665874108672142, 0.0013620989629998803, ...
3534a7d9eb7c0c9fe171ec4bb434345c9039f024
subsection
38
144
The universal pasture of a matroid
The support of M is the image point x_M of _M and the universal pasture of M is k_M=k(x_M)^\pm .More explicitly, we have\textstyle k_M \ = \ \big ({\mathbb {F}}_1^\pm \big [ \, x_I^\pm \, \big | \, I\in {\mathcal {I}}\, \big ]\!\sslash \!\operatorname{{Pl}}(r,E)\big )_0^\pmwhere \operatorname{{Pl}}(r,E) is generated by...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.015138348564505577, -0.011536885984241962, -0.03081081248819828, -0.0292389877140522, -0.03332878276705742, -0.028430184349417686, 0.02427934668958187, 0.0314975306391716, 0.03494638949632645, 0.028308100998401642, -0.04755150526762009, -0.018175173550844193, 0.02653789147734642, 0.0360...
e1441f94409782a00b02f721a3f13c69febc8c98
subsection
39
144
The universal pasture of a matroid
This means that factors into a uniquely determined morphism \operatorname{Spec}{\mathbb {K}}\rightarrow \operatorname{Spec}k(x) followed by \operatorname{Spec}k(x)\rightarrow \operatorname{Mat}(r,E). This yields a morphism k(x)\rightarrow {\mathbb {K}}, which extends uniquely to a morphism k(x)^\pm \rightarrow {\mathbb...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.033909015357494354, 0.004189029801636934, -0.029971783980727196, -0.0185416080057621, -0.048925429582595825, -0.023562340065836906, -0.019335158169269562, 0.013444573618471622, 0.01392528135329485, 0.05463288724422455, -0.017015550285577774, -0.012383962981402874, 0.031589407473802567, ...
cbc7be5172f09d151144b1338ec07e066c5f448f
subsection
40
144
The universal pasture of a matroid
Thus the morphism resulting from t_M^\ast with the canonical morphism \operatorname{Spec}k_M\rightarrow \operatorname{Mat}(r,E) must be equal to _M.Remark 2.6 As a consequence of Proposition REF and Corollary REF , we see that only the points x in the image of \Phi are supports of matroids.Lemma 2.7 Let k be a field a...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.0073420265689492226, -0.0011318163014948368, -0.054006803780794144, -0.024379342794418335, -0.02361653372645378, -0.051779404282569885, 0.028132358565926552, 0.032404083758592606, 0.01757509633898735, 0.030741160735487938, -0.03722503036260605, -0.04793485254049301, 0.014279765076935291, ...
4dd0007873c2ca940b5ec283fc28aa3666d9d8dd
subsection
41
144
The universal pasture of a matroid
By Lemma REF , this is equivalent to k(x)^\times =\lbrace 1,\rbrace , or k(x)={\mathbb {F}}_1^\pm , as claimed. Since {\mathbb {F}}_1^\pm is pasteurized and nonzero, Proposition REF implies that x is the support of a matroid.Example 2.10 (Support of the uniform matroid) The uniform matroid of rank r on E is the matroi...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.012862146832048893, -0.03640460595488548, -0.049709223210811615, -0.028104478493332863, -0.0146243991330266, -0.04134806618094444, 0.04284330829977989, 0.03719799965620041, 0.018080241978168488, 0.02679232507944107, -0.038906849920749664, -0.02364926226437092, 0.02705170400440693, 0.027...
fcdcbfca902697ebb412053b784970a59f25c892
subsection
42
144
Universal pastures for rank 2-matroids on the four element set
In the following, we characterize the different universal pastures that can occur for \operatorname{Mat}(2,E) where E=\lbrace 1,2,3,4\rbrace . Note that \operatorname{Mat}(2,E) is defined by a single Plücker relation, namely0 \ \leqslant \ x_{1,2}x_{3,4} \ + \ \cdot x_{1,3}x_{2,4} \ + \ x_{1,4}x_{2,3}where we write x_{...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.001733464770950377, 0.00009618441254133359, -0.06724851578474045, -0.007517401594668627, -0.037346724420785904, -0.04753774404525757, 0.03313606604933739, 0.0001756825513439253, -0.003236182266846299, 0.05339605361223221, -0.03774338215589523, -0.005270953290164471, 0.023006072267889977, ...
1a1cca59c4b4f4da0375d0636517c70d88d038e0
subsection
43
144
Case
By Corollary REF , we have k(x)^\pm =k(x)={\mathbb {F}}_1^\pm . In particular, x is the support of a matroid.By Lemma REF , we have x={\mathfrak {p}}_{\mathcal {I}} for a 2-subset {\mathcal {I}}=\lbrace I,J\rbrace of \binom{E}{r}. There are two cases. If I and J intersect nontrivially, thenk(x)^\pm \ = \ k(x) \ = \ {{\...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.03330381587147713, -0.0030678585171699524, -0.0291217602789402, -0.033059608191251755, -0.012156961485743523, -0.014637195505201817, 0.05427514761686325, 0.0273512564599514, 0.013316947966814041, 0.01976555585861206, -0.025214439257979393, -0.01205012109130621, 0.007444517221301794, -0....
b6e91981e9eb178345fbc7d7cc68bc1c6589a160
subsection
44
144
Case
If K and L intersect nontrivially, then we havek(x) \ = \ \big ({{\mathbb {F}}_1^\pm }[x_{I}^{\pm 1},x_{J}^{\pm 1},x_{K}^{\pm 1},x_{L}^{\pm 1}]\!\sslash \!\langle 0\leqslant 1 \rangle \big )_0and k(x)^\pm =\lbrace 0\rbrace , i.e. x is not the support of a matroid. If K\cap L=\emptyset , thenk(x) \ = \ \big ({{\mathbb {...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.00004256255488144234, 0.01622193679213524, -0.02600393258035183, -0.033756278455257416, -0.0159472469240427, -0.028918692842125893, 0.06586442142724991, 0.00042801001109182835, -0.0008412363822571933, 0.013734471052885056, -0.021013740450143814, -0.03906694054603577, -0.003183726686984300...
356375b7dbddc76de1bc76479928478fa606f5e4
subsection
45
144
Case
As in the rank 4-case, we havek(x)^\pm \ = \ k(x)\!\sslash \!\langle \equiv ^ix_Kx_Lx_I^{-1}x_J^{-1} \rangle \ \simeq \ {{\mathbb {F}}_1^\pm }[x_{I}^{\pm 1},x_{J}^{\pm 1},x_{K}^{\pm 1},x_{N}^{\pm 1}]_0.Thus x is the support of a matroid.By Lemma REF , we have x={\mathfrak {p}}_{\mathcal {I}} for {\mathcal {I}}=\binom{E...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.020447665825486183, 0.01171162910759449, -0.04583939537405968, -0.042634908109903336, -0.010712135583162308, -0.01091813761740923, 0.07379470765590668, 0.009163301438093185, 0.002681848593056202, 0.02346903644502163, -0.03628697618842125, -0.008507144637405872, 0.005321734119206667, -0....
a93714c1c91548a80872cc8cfb2aafa4e2cb3dac
subsection
46
144
Case
Thus we havek(x)^\pm \ = \ k(x) \ = \ {{\mathbb {F}}_1^\pm }[x_{I}^{\pm 1},x_{J}^{\pm 1},x_K^{\pm 1}]_0and x is the support of a matroid. If not—for instance, I\cap J=\emptyset — thenk(x) \ = \ \big ({{\mathbb {F}}_1^\pm }[x_{I}^{\pm 1},x_{J}^{\pm 1},x_{K}^{\pm 1}]\!\sslash \!\langle 0\leqslant 1 \rangle \big )_0,as in...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.00014773868315387517, 0.013728845864534378, -0.03029656410217285, -0.03876739367842674, -0.0026786131784319878, -0.02582457847893238, 0.06562983989715576, 0.005021445453166962, 0.007650454994291067, 0.021001547574996948, -0.01706375740468502, -0.03144127130508423, -0.007898474112153053, ...
74cdbf46ef5ad07d005d9811bf65cf11d8eb25b5
subsection
47
144
Case
Then we havek(x) \ = \ \big ({{\mathbb {F}}_1^\pm }[x_{I}^{\pm 1},x_{J}^{\pm 1},x_{K}^{\pm 1},x_{L}^{\pm 1},x_{N}^{\pm 1}]\!\sslash \!\langle 0\leqslant x_Ix_J+^ix_Kx_L \rangle \big )_0where i=0 or 1, depending on I, J, K and L. As in the rank 4-case, we havek(x)^\pm \ = \ k(x)\!\sslash \!\langle \equiv ^ix_Kx_Lx_I^{-1...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.005878853145986795, 0.035738542675971985, -0.040316496044397354, -0.061436112970113754, -0.016801083460450172, -0.03094695508480072, 0.06119195744395256, 0.006920337211340666, 0.001445869798772037, 0.011948454193770885, -0.022782940417528152, -0.015717634931206703, -0.008225053548812866, ...
019f58a4d6ad4f5a6ab7a4c8bb19a867fbbb0bd2
subsection
48
144
Realization spaces
Let k be a field. The realization space of a matroid M is the subset of the Grassmannian over k that consists of the subvector spaces whose associated matroid is M. These realization spaces have been used for proving that several moduli spaces, such as Hilbert schemes and moduli spaces of curves, can become arbitrarily...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 339, "openalex_id": "", "raw": "Ravi Vakil. Murphy's law in algebraic geometry: badly-behaved deformation spaces. Invent. Math., 164(3):569–590, 2006.", "source_ref_id": "72e72426b27a7e2d9320a034dc79e72f8ffffeac", "sta...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.01350321900099516, -0.023314030840992928, -0.043454427272081375, -0.019133374094963074, -0.021635666489601135, -0.039792533963918686, 0.02581632323563099, 0.01531890593469143, 0.03582548722624779, 0.04699425399303436, -0.03967047110199928, 0.0012883367016911507, 0.03140070661902428, 0.0...
76de6d8ebe060a76d0a28bd568d4944b228b5445
subsection
49
144
Realization spaces
In other words, \operatorname{Spec}k_M is the fine moduli space of realization spaces for M. In down-to-earth terms, this means the following:Theorem 2.14 Let M be a matroid and _M:\operatorname{Spec}k_M\rightarrow \operatorname{Mat}(r,E) the inclusion of the universal pasture k_M of M into the matroid space. Let F be...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1007/bfb0082792", "end": 1902, "openalex_id": "https://openalex.org/W94985437", "raw": "Nikolai E. Mnëv. The universality theorems on the classification problem of configuration varieties and convex polytopes varieties. In Topology and g...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.026984624564647675, -0.015421964228153229, -0.041308287531137466, -0.02445243112742901, -0.023491419851779938, -0.034993063658475876, 0.002781979041174054, -0.030081219971179962, 0.03419984504580498, 0.04747097194194794, -0.03709813579916954, -0.00567836407572031, 0.013965191319584846, ...
71e741c1f15f8027b17711d977e9061808068bd0
subsection
50
144
Realization spaces
In this section, we show that realization spaces are the same as morphism sets from universal pastures.Let \Delta :\binom{E}{r}\rightarrow {\mathbb {K}} be a Grassmann-Plücker function, M=[\Delta ] the corresponding matroid and _M:{\mathbb {K}}\rightarrow \operatorname{Mat}(r,E) its characteristic morphism. Let F be a ...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.01693621277809143, -0.022596873342990875, -0.04021969065070152, -0.01392278727144003, -0.035245630890131, -0.025404317304491997, 0.01606651395559311, 0.010825444012880325, 0.027189485728740692, 0.043790027499198914, -0.043057650327682495, 0.02360389195382595, 0.02047603204846382, 0.0291...
deabee60110f6b8e5470900905cc2727b20916c3
subsection
51
144
Realization spaces
Let F be a pasture. The map\begin{array}{cccc} _{M,\ast }: & \operatorname{Hom}(k_M,F) & \longrightarrow & {\mathcal {X}}_M(F) \\ & f & \longmapsto & _M\circ f^\ast \end{array}is a bijection that is functorial in F.We will show that every morphism :\operatorname{Spec}F\rightarrow \operatorname{Mat}(r,E) in {\mathcal {X...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1007/bfb0082792", "end": 1590, "openalex_id": "https://openalex.org/W94985437", "raw": "Nikolai E. Mnëv. The universality theorems on the classification problem of configuration varieties and convex polytopes varieties. In Topology and g...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.026793383061885834, 0.0021285174880176783, -0.015807485207915306, -0.0069996947422623634, -0.012809251435101032, -0.03092835284769535, -0.009078623726963997, -0.013686597347259521, 0.027983522042632103, 0.03951871395111084, -0.04669006168842316, -0.025557469576597214, 0.024535169824957848...
cddb93ce1d157168aecbe3364537bc686f4ff03f
subsection
52
144
The weak matroid space
There is a variant of the matroid space for weak matroids, which leads to the notion of the weak universal pasture of a matroid. Although it turns out that the weak matroid space is not a moduli space for weak matroids, it turns out that the universal pasture is a very useful object for matroid theory for its connectio...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.aim.2018.12.004", "end": 1397, "openalex_id": "https://openalex.org/W2962744969", "raw": "Matthew Baker and Nathan Bowler. Matroids over partial hyperstructures. Preprint, arXiv:1709.09707, 2017.", "source_ref_id": "c29f3f46...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.0262564979493618, -0.019772469997406006, -0.04610525071620941, -0.012662924826145172, 0.009703156538307667, -0.06639644503593445, 0.015836283564567566, 0.02360185980796814, 0.003219129052013159, 0.051567088812589645, -0.056144051253795624, -0.0015189788537099957, 0.007551985327154398, 0...
7510118934a4e55fa5ec36720cfe38f390f6f57f
subsection
53
144
The weak matroid space
This justifies our abuse of terminology.Definition 2.17 The weak matroid space of rank r on E is the ordered blue scheme\textstyle \operatorname{Mat}^w(r,E) \quad = \quad \operatorname{Proj}\Big ( \, {\mathbb {F}}_1^\pm \big [ \, x_I \, \big | \, I\in \binom{E}{r} \, \big ]\!\sslash \!\operatorname{{Pl}}^w(r,E) \, \Big...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.0029113232158124447, -0.006063031032681465, -0.006177499890327454, -0.029075076803565025, 0.005650943145155907, -0.006814709398895502, 0.02434369921684265, 0.027777763083577156, 0.02963978797197342, 0.05491450056433678, -0.011645292863249779, -0.010409030131995678, -0.01848289556801319, ...
b98bcabd5fb8238b90d06997d29fc8b0a0cbbd68
subsection
54
144
The weak matroid space
The weak characteristic morphism is the morphism _M^w=^w\circ _M:\operatorname{Spec}{\mathbb {K}}\rightarrow \operatorname{Mat}^w(r,E). The weak support of M is the image x_M^w=^w(x_M) of x_M in \operatorname{Mat}^w(r,E). The weak universal pasture of M is the pasteurization k_M^w=k(x_M^w)^\pm of the residue field k(x^...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.029211480170488358, 0.012423273175954819, -0.004635834600776434, -0.02931831404566765, -0.02388503961265087, -0.0712430477142334, 0.015796177089214325, 0.035194188356399536, 0.022709865123033524, 0.07740889489650726, -0.02574700489640236, -0.041421085596084595, 0.025441765785217285, 0.0...
3494bb9a0ac1ae2fd25e7426ef64aaae377468ab
subsection
55
144
The weak matroid space
Then the map\begin{array}{cccc} _{M,\ast }^w: & \operatorname{Hom}(k_M^w,F) & \longrightarrow & {\mathcal {X}}_M^w(F) \\ & f & \longmapsto & _M^w\circ f^\ast \end{array}is a bijection.The proof is analogous to that of the corresponding result for strong F-matroids, see Theorem REF . For completeness, we outline the ide...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.030616747215390205, -0.005509793758392334, -0.01275189034640789, -0.05341905355453491, -0.02474065311253071, -0.02034502662718296, 0.02745739184319973, 0.006509493105113506, 0.007074208930134773, 0.053999029099941254, -0.027991583570837975, -0.011477464810013771, 0.028876813128590584, 0...
975765f60bdd073367ba8a05e40828f32d3c70a6
subsection
56
144
The weak matroid space
Consider the 3-term Plücker relation0 \ \leqslant \ \Delta (I_{1,2}) \, \Delta (I_{3,4}) \ + \ \, \Delta (I_{1,3}) \, \Delta (I_{2,4}) \ + \ \Delta (I_{1,4}) \, \Delta (I_{2,3})for I=\lbrace i_0\rbrace and i_1<i_2<i_3<i_4 with i_1,i_2,i_3,i_4\notin \lbrace i_0\rbrace , where I_{k,l}=\lbrace i_0,i_k,i_l\rbrace . In orde...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.05284872651100159, 0.048363298177719116, -0.06773912906646729, -0.02801104635000229, -0.014135204255580902, 0.032923657447099686, 0.04165041074156761, 0.020153917372226715, -0.020291225984692574, -0.0005964362062513828, -0.03267955407500267, 0.00822328682988882, 0.005778422579169273, -0...
4736a34e3632fdf4360c0bfcb3ebfbe37bb12d95
subsection
57
144
The weak matroid space
Therefore \Delta is not a weak Grassmann-Plücker function.Let {\mathcal {I}} be the complement of \lbrace J,J^c\rbrace in \binom{E}{r} and x^w={\mathfrak {p}}_{\mathcal {I}} the corresponding point of the weak matroid space \operatorname{Mat}^w(3,E). Since all 3-term Plücker relations for \Delta are trivial, the residu...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.aim.2018.12.004", "end": 2067, "openalex_id": "https://openalex.org/W2962744969", "raw": "Matthew Baker and Nathan Bowler. Matroids over partial hyperstructures. Preprint, arXiv:1709.09707, 2017.", "source_ref_id": "c29f3f46...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.050283461809158325, -0.007788139395415783, -0.05199212208390236, -0.04030609875917435, -0.02242618054151535, -0.04845275357365608, 0.034264761954545975, 0.010435039177536964, -0.010770668275654316, 0.03113730065524578, -0.035302162170410156, 0.000444566598162055, 0.020473424345254898, 0...
5ef87b6e43fd6c077e3fac28a436c6942f7152e4
subsection
58
144
The weak matroid space
For instance, the phase hyperfield, which is the hyperfield quotient of by {\mathbb {R}}^\times , admits weak matroids that are not strong. See Example 2.36 in for details.In the following, we shall call a pasture F perfect if the associated tract F^\textup {tract} is perfect. Since the matroid theories of F and F^\tex...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.aim.2018.12.004", "end": 174, "openalex_id": "https://openalex.org/W2962744969", "raw": "Matthew Baker and Nathan Bowler. Matroids over partial hyperstructures. Preprint, arXiv:1709.09707, 2017.", "source_ref_id": "c29f3f46a...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.0131427813321352, -0.011418888345360756, -0.00209003034979105, -0.01349366270005703, 0.01864246092736721, -0.043905891478061676, 0.01392082218080759, 0.04286850616335869, -0.002137704286724329, 0.06938290596008301, -0.03200644999742508, -0.023432748392224312, 0.0011594328097999096, 0.00...
16ba7d0d76b7de7bc86866d7ebc2520633f671f5
subsection
59
144
The weak matroid space
Let {\mathcal {L}}^w_\textup {univ}=^\ast ({\mathcal {O}}(1)) be the pullback of the tautological bundle {\mathcal {O}}(1) on {\mathbb {P}}^N_{{\mathbb {F}}_1^\pm } to \operatorname{Mat}^w(r,E).The identity map induces a morphism\textstyle {\mathbb {F}}_1^\pm \big [ \, x_I \, \big | \, I\in \binom{E}{r} \, \big ]\!\ssl...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.02256206050515175, 0.026452070102095604, -0.010464890860021114, -0.030982788652181625, -0.03966285288333893, -0.03920520469546318, 0.002406467217952013, 0.020487388595938683, 0.02977764792740345, 0.06333852559328079, -0.02555202879011631, -0.023385826498270035, 0.009915713220834732, -0....
07bfc6201b9af1d93da92cbce78d8bf9e5bc2dad
subsection
60
144
The weak matroid space
The weak realization space of M over F is the set{\mathcal {X}}_M^w(F) \ = \ \big \lbrace \, :\operatorname{Spec}F\rightarrow \operatorname{Mat}^w(r,E) \, \big | \, \circ t_F^\ast =_M^w \, \big \rbraceof all weak F-matroids that represent M.Recall from Remark REF the definition of a perfect pasture.Lemma 2.20 Let M be...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.019881585612893105, -0.0069501628167927265, -0.018523596227169037, -0.02816685102880001, -0.016112782061100006, -0.03719977289438248, 0.02891450934112072, 0.0235283225774765, 0.05135949328541756, 0.07293475419282913, -0.042601220309734344, -0.024794762954115868, 0.019698485732078552, 0....
1604c10bc864d1ead72013654bfe6da042f9ff6d
subsection
61
144
The weak matroid space
Since the locus of points of \operatorname{Mat}^w(r,E) supporting matroids is not locally closed, but merely constructible in general, this locus does not inherit a scheme structure from \operatorname{Mat}^w(r,E) in an obvious way.For instance, it is a well-known fact that the 3-term Plücker relations do not suffice, i...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.026279281824827194, 0.002100282348692417, -0.0471561998128891, -0.029072027653455734, -0.013765337876975536, -0.02846159040927887, 0.0331772118806839, 0.015161710791289806, -0.039159487932920456, 0.01956448145210743, -0.021594183519482613, 0.009629632346332073, 0.002601984655484557, 0.0...
d6b735728289dbef5dd41a534a7c1ebf60716440
subsection
62
144
The weak matroid space
The Plücker relation for I and I^{\prime } is0 \ \leqslant \ \sum _{k=1}^4 ^k \cdot \overline{\Delta }(I\cup \lbrace j_k\rbrace ) \cdot \overline{\Delta }(I^{\prime }-\lbrace j_k\rbrace )where =1. The sum on the right hand side has precisely one nonzero term, namely\overline{\Delta }(I\cup \lbrace j_l\rbrace ) \cdot \o...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.03269253298640251, 0.024069150909781456, -0.060928378254175186, -0.06520191580057144, -0.030952593311667442, -0.009004945866763592, 0.04084277153015137, 0.03318093717098236, -0.001745662186294794, 0.00405222550034523, -0.03540927916765213, -0.0038042080122977495, 0.023321283981204033, -...
c55aa9fa6ec512727fd7fafff5546e7a676742e3
subsection
63
144
The Tutte group
The Tutte group is introduced by Dress and Wenzel in and used as a tool to study the representability of matroids and to provide cryptomorphisms for matroids over fuzzy rings, cf. . In this section, we show that the Tutte group is precisely the unit group of the weak universal pasture.For the following characterization...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/0001-8708(89)90013-3", "end": 182, "openalex_id": "https://openalex.org/W2086795154", "raw": "Andreas W. M. Dress and Walter Wenzel. Geometric algebra for combinatorial geometries. Adv. Math., 77(1):1–36, 1989.", "source_ref_i...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.03983435407280922, 0.030768603086471558, -0.05237988382577896, 0.02966972440481186, -0.0011084175202995539, -0.07783724367618561, 0.03195905685424805, 0.0487169548869133, 0.0001161954496637918, 0.05442501977086067, -0.05097576230764389, -0.016498442739248276, 0.001898236689157784, 0.006...
7255b049f2d82173097cec4375ead62ccdec738d
subsection
64
144
The Tutte group
As explained in the proof of Lemma REF , we have x_M={\mathfrak {p}}_{{\mathcal {B}}^c} where {\mathcal {B}}^c is the complement of {\mathcal {B}} in \binom{E}{r}, andk(x_M^w)^\times \ = \ k(x_M)^\times \ = \ \Big \lbrace \, ^i \, \cdot \, \prod _{I\in {\mathcal {B}}} \ x_I^{e_I} \, \Big | \, i\in \lbrace 0,1\rbrace ,e...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.025165226310491562, 0.0166191216558218, -0.0052497498691082, -0.019884955137968063, -0.01787051558494568, -0.03699242323637009, 0.04166226089000702, 0.023578092455863953, 0.0024589127860963345, 0.055549681186676025, -0.05158184468746185, -0.051734454929828644, -0.0048491512425243855, 0....
bda0318efae8089da0d91d61b1cdbf5c99f5128f
subsection
65
144
The Tutte group
To enable ourselves to work with degree-0 elements, we will work with two graded abelian groups G_M^{\prime } and H_M, which contain M and (k_M^w)^\times , respectively, as subquotients.Namely, we define G_M^{\prime } as the abelian group generated by the symbols and X_{(i_1,\cdots ,i_r)} for every (i_1,\cdots ,i_r)\in...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.011319664306938648, -0.013813956640660763, -0.02511073648929596, -0.01803213357925415, -0.011426453478634357, -0.040762994438409805, 0.03850516304373741, 0.031579118221998215, -0.005884852260351181, 0.014569109305739403, -0.036796536296606064, -0.02942807599902153, -0.012753691524267197, ...
1e1f9f27a1839fb395fcba9a090488cb71676450
subsection
66
144
The Tutte group
Thus the theorem follows if we can show that the isomorphism f identifies \ker h with \ker g.As our next step, we exhibit a set of generators for \ker h. The kernel of h consists of all weak inverses of 1 in k(x_M^w). Such elements must come from the 3-term Plücker relation0 \leqslant x_{I,1,2} \, x_{I,3,4} \ + \ \, x_...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.037591397762298584, 0.0019327759509906173, -0.011869361624121666, 0.004519663751125336, -0.022777579724788666, 0.008337539620697498, 0.055624280124902725, 0.004771391861140728, 0.0018822395941242576, 0.011602376587688923, -0.04113084450364113, -0.016507260501384735, 0.0002781881485134363,...
a9cc5e57df010a3063feb8e21c5165959e0cdb6b
subsection
67
144
The Tutte group
In the following, we will show that f maps this set to the set of generators for \ker g that we used in the definition of G_M=G_M^{\prime }/\ker g.Let j_1,\cdots ,j_{r-2},k_1,k_2,l_1,l_2 be pairwise different elements of E, and define I=\lbrace j_1,\cdots ,j_{r-2}\rbrace and \lbrace i_1,i_2,i_3,i_4\rbrace =\lbrace k_1,...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.016845006495714188, -0.007888467982411385, -0.041258059442043304, -0.006591523997485638, -0.0037515994627028704, -0.02865482121706009, 0.017150169238448143, 0.00962026882916689, -0.014617315493524075, 0.023100851103663445, -0.037718165665864944, -0.028334399685263634, -0.03231677785515785...
0e0c6e4333a290fb6b8c82b8f3efd21b50c1191e
subsection
68
144
The Tutte group
For instance, if j_1<\cdots <j_{r-2}, then we haveN \ = \ \sum _{i\in \lbrace k_1,k_2,l_1,l_2\rbrace } \#\lbrace j\in I|i<j\rbrace .From these considerations, we obtain the equality\frac{X_{(j_1,\cdots ,j_{r-2},k_p,l_q)} \, X_{(j_1,\cdots ,j_{r-2},k_{p^{\prime }},l_{q^{\prime }})}}{X_{(j_1,\cdots ,j_{r-2},k_p,l_{q^{\pr...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.07759015262126923, 0.02194623090326786, -0.035376470535993576, 0.009912431240081787, -0.03726891055703163, 0.045449148863554, 0.03156106173992157, -0.006005452945828438, -0.030111204832792282, -0.005372095387428999, -0.033300887793302536, -0.034613385796546936, -0.036170072853565216, -0...
f9a687dfc8cb308d96802006eeede72f61bbe255
subsection
69
144
The Tutte group
We obtain\frac{X_{(j_1,\cdots ,j_{r-2},k_1,l_1)} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{2})}}{X_{(j_1,\cdots ,j_{r-2},k_1,l_{2})} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{1})}} \quad = \quad \frac{X_{I\cup \lbrace i_1,i_3\rbrace } \, X_{I\cup \lbrace i_2,i_4\rbrace }}{X_{I\cup \lbrace i_1,i_4\rbrace } \, X_{I\cup \lbrace i_2,i...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.08662649244070053, 0.012720786035060883, -0.028799189254641533, -0.0014632338425144553, -0.026128357276320457, 0.045114148408174515, 0.029485974460840225, 0.018665293231606483, -0.017062794417142868, -0.010690954513847828, -0.039131488651037216, -0.003641868708655238, -0.00612383382394909...
7cc40d1d9313df4df0faa8c880e967ebd2d466f7
subsection
70
144
The Tutte group
Since ^2=1, we have\frac{X_{(j_1,\cdots ,j_{r-2},k_1,l_1)} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{2})}}{X_{(j_1,\cdots ,j_{r-2},k_1,l_{2})} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{1})}} \quad = \quad \frac{X_{I\cup \lbrace i_1,i_2\rbrace } \, X_{I\cup \lbrace i_3,i_4\rbrace }}{X_{I\cup \lbrace i_1,i_3\rbrace } \, X_{I\cup \lb...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/0001-8708(89)90013-3", "end": 872, "openalex_id": "https://openalex.org/W2086795154", "raw": "Andreas W. M. Dress and Walter Wenzel. Geometric algebra for combinatorial geometries. Adv. Math., 77(1):1–36, 1989.", "source_ref_i...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.0820319652557373, 0.020813170820474625, -0.034241024404764175, 0.028473149985074997, 0.003761324565857649, -0.03286771848797798, 0.02743554301559925, 0.037048663944005966, -0.026214828714728355, 0.03778109326958656, -0.05044599995017052, -0.028183231130242348, 0.003568680491298437, -0.0...
7dda119fa0b879d2583f1d903ca162b44b32fc97
subsection
71
144
The Tutte group
The Tutte group M of M is defined as the subgroup of G_M that is generated by and elements of the form X_{(i_1,\cdots ,i_r)}X_{(j_1,\cdots ,j_r)}^{-1} with \lbrace i_1,\cdots ,i_r\rbrace ,\lbrace j_1,\cdots ,j_r\rbrace \in {\mathcal {B}}.Let x_M be the support of M and x_M^w its weak support. The natural map k(x_M^w)\r...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.0013576589990407228, 0.0006344958092086017, -0.04719771817326546, 0.008252736181020737, -0.01682581938803196, -0.04866215959191322, 0.01656649075448513, 0.03850260004401207, 0.015498668886721134, 0.0325838178396225, -0.04994354769587517, -0.062421806156635284, -0.021127615123987198, 0.01...
68e8ea827d51a4b3334b2df72dbac8569ea67502
subsection
72
144
The Tutte group
To enable ourselves to work with degree-0 elements, we will work with two graded abelian groups G_M^{\prime } and H_M, which contain M and (k_M^w)^\times , respectively, as subquotients.Namely, we define G_M^{\prime } as the abelian group generated by the symbols and X_{(i_1,\cdots ,i_r)} for every (i_1,\cdots ,i_r)\in...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.011319664306938648, -0.013813956640660763, -0.02511073648929596, -0.01803213357925415, -0.011426453478634357, -0.040762994438409805, 0.03850516304373741, 0.031579118221998215, -0.005884852260351181, 0.014569109305739403, -0.036796536296606064, -0.02942807599902153, -0.012753691524267197, ...
30ee6e2bb4a996cef6853deb0937968076d4670d
subsection
73
144
The Tutte group
Thus the theorem follows if we can show that the isomorphism f identifies \ker h with \ker g.As our next step, we exhibit a set of generators for \ker h. The kernel of h consists of all weak inverses of 1 in k(x_M^w). Such elements must come from the 3-term Plücker relation0 \leqslant x_{I,1,2} \, x_{I,3,4} \ + \ \, x_...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.037591397762298584, 0.0019327759509906173, -0.011869361624121666, 0.004519663751125336, -0.022777579724788666, 0.008337539620697498, 0.055624280124902725, 0.004771391861140728, 0.0018822395941242576, 0.011602376587688923, -0.04113084450364113, -0.016507260501384735, 0.0002781881485134363,...
ff078215ae19161e569d6613127179c67df7fe14
subsection
74
144
The Tutte group
In the following, we will show that f maps this set to the set of generators for \ker g that we used in the definition of G_M=G_M^{\prime }/\ker g.Let j_1,\cdots ,j_{r-2},k_1,k_2,l_1,l_2 be pairwise different elements of E, and define I=\lbrace j_1,\cdots ,j_{r-2}\rbrace and \lbrace i_1,i_2,i_3,i_4\rbrace =\lbrace k_1,...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.016845006495714188, -0.007888467982411385, -0.041258059442043304, -0.006591523997485638, -0.0037515994627028704, -0.02865482121706009, 0.017150169238448143, 0.00962026882916689, -0.014617315493524075, 0.023100851103663445, -0.037718165665864944, -0.028334399685263634, -0.03231677785515785...
b70f5c17d254d0011ddbae213ad13d43e378458e
subsection
75
144
The Tutte group
For instance, if j_1<\cdots <j_{r-2}, then we haveN \ = \ \sum _{i\in \lbrace k_1,k_2,l_1,l_2\rbrace } \#\lbrace j\in I|i<j\rbrace .From these considerations, we obtain the equality\frac{X_{(j_1,\cdots ,j_{r-2},k_p,l_q)} \, X_{(j_1,\cdots ,j_{r-2},k_{p^{\prime }},l_{q^{\prime }})}}{X_{(j_1,\cdots ,j_{r-2},k_p,l_{q^{\pr...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.07759015262126923, 0.02194623090326786, -0.035376470535993576, 0.009912431240081787, -0.03726891055703163, 0.045449148863554, 0.03156106173992157, -0.006005452945828438, -0.030111204832792282, -0.005372095387428999, -0.033300887793302536, -0.034613385796546936, -0.036170072853565216, -0...
7bc4bddedd5aebb00337080d6227af3071f31f2b
subsection
76
144
The Tutte group
We obtain\frac{X_{(j_1,\cdots ,j_{r-2},k_1,l_1)} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{2})}}{X_{(j_1,\cdots ,j_{r-2},k_1,l_{2})} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{1})}} \quad = \quad \frac{X_{I\cup \lbrace i_1,i_3\rbrace } \, X_{I\cup \lbrace i_2,i_4\rbrace }}{X_{I\cup \lbrace i_1,i_4\rbrace } \, X_{I\cup \lbrace i_2,i...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.08662649244070053, 0.012720786035060883, -0.028799189254641533, -0.0014632338425144553, -0.026128357276320457, 0.045114148408174515, 0.029485974460840225, 0.018665293231606483, -0.017062794417142868, -0.010690954513847828, -0.039131488651037216, -0.003641868708655238, -0.00612383382394909...
bb0849b898280fc77d18b0151af59f106f40d4d1
subsection
77
144
The Tutte group
Since ^2=1, we have\frac{X_{(j_1,\cdots ,j_{r-2},k_1,l_1)} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{2})}}{X_{(j_1,\cdots ,j_{r-2},k_1,l_{2})} \, X_{(j_1,\cdots ,j_{r-2},k_{2},l_{1})}} \quad = \quad \frac{X_{I\cup \lbrace i_1,i_2\rbrace } \, X_{I\cup \lbrace i_3,i_4\rbrace }}{X_{I\cup \lbrace i_1,i_3\rbrace } \, X_{I\cup \lb...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.08269700407981873, 0.0060992855578660965, -0.013503109104931355, 0.006064955610781908, -0.018629712983965874, 0.03426890820264816, 0.020445385947823524, 0.00585516169667244, -0.0036103653255850077, -0.000006973268682486378, -0.0320717915892601, -0.02708250656723976, -0.008971557021141052,...
902c24c8b5c6b4ad8d1d92a5be3cb5cb9272fdbc
subsection
78
144
Cross ratios and rescaling classes
In this section, we will define and study the properties of the foundation of a matroid, which is a subpasture of the weak universal pasture that is closely related to the inner Tutte group from and the universal partial field from .The key notions in this section are cross ratios, rescaling classes, fundamental elemen...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/0001-8708(89)90013-3", "end": 234, "openalex_id": "https://openalex.org/W2086795154", "raw": "Andreas W. M. Dress and Walter Wenzel. Geometric algebra for combinatorial geometries. Adv. Math., 77(1):1–36, 1989.", "source_ref_i...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.013210508041083813, -0.0005186573835089803, -0.034841571003198624, 0.012951179407536983, -0.01801571622490883, -0.048540227115154266, 0.050919950008392334, 0.05320814251899719, 0.011227406561374664, 0.07297813892364502, -0.05131657049059868, -0.0011574449017643929, -0.01056382991373539, ...
c1362ed645fb0b773beba8250953101c2b44f82c
subsection
79
144
Cross ratios
The study of cross ratios of four points on a line belongs to the oldest themes in mathematics and finds its earliest traces in the writings of Pappus of Alexandria (). Its main property is that it is invariant under projective transformation and that it characterizes the ratios of the pairwise differences between the ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1007/978-1-4612-4908-5", "end": 168, "openalex_id": "https://openalex.org/W2490731174", "raw": "Pappus of Alexandria. Book 7 of the Collection, volume 8 of Sources in the History of Mathematics and Physical Sciences. Springer-Verlag, New...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.006013268604874611, 0.01433874573558569, -0.0724644660949707, 0.006795451510697603, 0.008088914677500725, 0.005902618169784546, 0.025854002684354782, 0.03244723007082939, 0.013545116409659386, 0.014712667092680931, -0.0870550349354744, 0.0013869436224922538, 0.016208354383707047, -0.011...
90d85ecb859e639abf4a9ad79c65f093ab84c4a8
subsection
80
144
Cross ratios
Then the cross ratio satisfies the relations\operatorname{Cr}_\Delta \big (.{\mathcal {I}}\big ) \ = \ \operatorname{Cr}_\Delta ({\mathcal {I}}) \qquad \text{and} \qquad \operatorname{Cr}_\Delta \big (.{\mathcal {I}}\big ) \ = \ \operatorname{Cr}_\Delta ({\mathcal {I}})^{-1}for every in the Klein four group V=\big \lbr...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.013966163620352745, 0.028496770188212395, -0.05479678511619568, -0.008992957882583141, -0.020808134227991104, 0.017162133008241653, 0.050921957939863205, 0.022959120571613312, 0.003415264654904604, 0.0043286713771522045, -0.061936233192682266, 0.0006416731048375368, -0.010548992082476616,...
052c5a58c6164e0cf5f6572592e88d3bf3c9b468
subsection
81
144
Cross ratios
Thus \Delta satisfies the 3-term Grassmann-Plücker relation0 \ \leqslant \ \Delta _{I,(1),(2)} \ \Delta _{I,(3),(4)} \ + \ \ \Delta _{I,(1),(3)} \ \Delta _{I,(2),(4)} \ + \ \Delta _{I,(1),(4)} \ \Delta _{I,(2),(3)}where \Delta _{I,k,l}=\Delta \big (I\cup \lbrace i_k,i_l\rbrace \big ) and is the permutation determined b...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1007/978-1-4612-4908-5", "end": 1519, "openalex_id": "https://openalex.org/W2490731174", "raw": "Pappus of Alexandria. Book 7 of the Collection, volume 8 of Sources in the History of Mathematics and Physical Sciences. Springer-Verlag, Ne...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.03325651213526726, 0.038809433579444885, -0.05321041867136955, -0.015423089265823364, -0.00858872290700674, 0.025766169652342796, 0.035422760993242264, 0.011990650556981564, 0.0009110263199545443, 0.0014626000775024295, -0.059556618332862854, 0.021540457382798195, 0.004916014149785042, ...
34d42a2ddc3975a31e98401b62d0934016d8a6ed
subsection
82
144
Cross ratios
For more details on the developments of cross ratios in general and explanations of their relevance for matroid theory, we refer to the book of Richter-Gebert.Let F be a pasture and M a matroid of rank r on E. The cross ratios of M in F are indexed by certain quadrangles or 4-cycles in the basis exchange graph of M.We ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 160, "openalex_id": "", "raw": "Jürgen Richter-Gebert. Perspectives on projective geometry. Springer, Heidelberg, 2011. A guided tour through real and complex geometry.", "source_ref_id": "9434a76bfdbf97a0f4fc1b80367b1f536dd...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.0024809804745018482, -0.01465323194861412, -0.061542049050331116, 0.012936949729919434, -0.0007279894780367613, 0.008756850846111774, 0.03993978351354599, 0.027201158925890923, -0.006990987341850996, 0.01766625978052616, -0.07780477404594421, -0.005110705737024546, -0.0017220026347786188, ...
c039b7a94dc8c58cbbf786adabdb120603a3a578
subsection
83
144
Cross ratios
If {\mathcal {I}} is non-degenerate, then \operatorname{Cr}_\Delta (.{\mathcal {I}}) is defined for all permutations and we have the identity\operatorname{Cr}_\Delta ({\mathcal {I}}) \ \cdot \ \operatorname{Cr}_\Delta \big ((123).{\mathcal {I}}\big ) \ \cdot \ \operatorname{Cr}_\Delta \big ((321).{\mathcal {I}}\big ) \...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.04931299015879631, 0.018736494705080986, -0.05208989977836609, -0.02068948559463024, -0.026350103318691254, -0.011595876887440681, 0.04046350717544556, 0.029584743082523346, 0.01381587702780962, 0.002544226823374629, -0.0630449503660202, 0.00024722295347601175, -0.004993092734366655, 0....
6e0b44a8325fb7771fea8487903d0354bf0e4d21
subsection
84
144
Cross ratios
After dividing by \Delta _{I,1,4}\Delta _{I,2,3}, we conclude that \operatorname{Cr}_\Delta ({\mathcal {I}})\in \lbrace 1,\rbrace , as claimed.If {\mathcal {I}} is non-degenerate, then all three terms are nonzero. After multiplying by appropriate powers of , this yields0 \ \leqslant \ \Delta _{I,1,2} \ \Delta _{3,4} \ ...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.0408085361123085, 0.062357399612665176, -0.030064629390835762, -0.02508946694433689, -0.008225805126130581, 0.015688547864556313, 0.043921828269958496, 0.021838825196027756, 0.0005207895883359015, -0.002043097512796521, 0.002287277253344655, 0.0026421009097248316, -0.020480575039982796, ...
b463a33526652bca1ab2d946ccea7c1d8e395421
subsection
85
144
Foundations
Pendavingh and van Zwam exhibit in the role of fundamental elements for the representability of matroids over partial fields. In this section, we extend this concept to pasteurized ordered blueprints, which makes this theory applicable to matroids over all pastures. Since there is a discrepancy between the signs of cro...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.jctb.2010.04.002", "end": 126, "openalex_id": "https://openalex.org/W2010114044", "raw": "Rudi A. Pendavingh and Stefan H. M. van Zwam. Confinement of matroid representations to subsets of partial fields. J. Combin. Theory Ser. B,...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.0266173854470253, -0.014209166169166565, -0.03577474132180214, 0.007245759014040232, -0.017307406291365623, -0.06520038098096848, 0.05494414269924164, -0.003138302592560649, -0.018024731427431107, 0.04810665175318718, -0.03275281563401222, -0.013018709607422352, 0.03247809410095215, 0.02...
692781ed277ea620d2dd9c3d113f90ccb376fad3
subsection
86
144
Foundations
The foundation of M is the subpasture k_M^f=(k_M^w)^\textup {found} of k_M^w.Let \Delta :\binom{E}{r}\rightarrow k_M^w be the weak Grassmann-Plücker function with \Delta (I)=x_I/x_{I_0} for some fixed basis I_0 of M. The universal cross ratio function of M is the function \operatorname{Cr}_M^\textup {univ}:\Omega _M\ri...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.013966536149382591, 0.013997047208249569, -0.065660260617733, -0.0398782379925251, -0.020808689296245575, -0.017284637317061424, 0.015171731822192669, 0.0052708229050040245, 0.016704922541975975, 0.012578273192048073, -0.060778457671403885, 0.0062662530690431595, 0.009305939078330994, 0...
84d25fb641726df5acabbc667b94f06943a9d5b5
subsection
87
144
Foundations
Theorem REF .In case of the uniform matroid M, it is easily seen that its foundation isk_M^f \ = \ {{\mathbb {F}}_1^\pm }[T_1^\pm ,T_2^\pm ]\!\sslash \!\langle 0\leqslant T_1+T_2+1 \ranglewhere T_1 and T_2 stand for the cross ratiosT_1 \ = \ \frac{x_{1,2}x_{3,4}}{x_{1,4}x_{2,3}} \quad \text{and} \quad T_2 \ = \ \frac{x...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.jctb.2010.04.002", "end": 719, "openalex_id": "https://openalex.org/W2010114044", "raw": "Rudi A. Pendavingh and Stefan H. M. van Zwam. Confinement of matroid representations to subsets of partial fields. J. Combin. Theory Ser. B,...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.02797665446996689, -0.0054877870716154575, -0.01940365694463253, -0.001139316475018859, -0.008687407709658146, -0.05137697607278824, 0.0289224311709404, 0.007795022334903479, -0.011623888276517391, 0.03929545357823372, -0.03706830367445946, -0.02875463105738163, 0.030493639409542084, 0.0...
fafcfd66e9d0591e2474f6d5d171a866dc7104c6
subsection
88
144
Foundations
An effective upper bound for the number of fundamental elements, depending only on the rank of R^\times as an abelian group, is given in . There is a similar result for characteristic p>0 if one counts solutions up to p-th powers; cf. .The relevance of fundamental elements and foundations for matroid theory is that the...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.4064/aa-78-2-189-199", "end": 139, "openalex_id": "https://openalex.org/W2157436851", "raw": "Frits Beukers and Hans P. Schlickewei. The equation x+y=1 in finitely generated groups. Acta Arith., 78(2):189–199, 1996.", "source_ref_i...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.015803879126906395, 0.0023187159094959497, -0.04765571281313896, -0.030051779001951218, -0.026588959619402885, -0.0471065454185009, 0.04927271232008934, -0.019266698509454727, -0.00527431583032012, 0.021798981353640556, -0.05851706862449646, 0.005575596354901791, 0.014324172399938107, 0....
5a407bc9299b52023411077cf7db2334438367d9
subsection
89
144
Foundations
Recall that there is a unique Plücker relation in this case, which is0 \ \leqslant \ x_{1,2}x_{3,4} \ + \ \cdot x_{1,3}x_{2,4} \ + \ x_{1,4}x_{2,3}where we write x_{i,j} for x_{\lbrace i,j\rbrace }. If any of the three terms is zero, then all cross ratios are 1 or by Lemma REF and thus k_M^f={{\mathbb {F}}_1^\pm }. Fro...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.019711310043931007, 0.009008923545479774, -0.054618027061223984, -0.03826313093304634, -0.010221809148788452, 0.003821736201643944, 0.024959523230791092, -0.001120394212193787, 0.009451359510421753, 0.023632213473320007, -0.05498418211936951, -0.014760597608983517, 0.023571187630295753, ...
f22ccb30ae3d78012ea35ef83eb4e2f7389e3e99
subsection
90
144
The inner Tutte group
Let M be a matroid of rank r on E and {\mathcal {B}} the set of bases of M. As a consequence of Theorem REF , the Tutte group M of M is isomorphic to the abelian group generated by and \prod _{I\in {\mathcal {B}}} X_I^{e_I} with \sum e_I=0 modulo the relations ^2=1 and\frac{X_{I,1,2}\ X_{I,3,4}}{X_{I,2,3}\ X_{I,4,1}} \...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/0001-8708(89)90013-3", "end": 564, "openalex_id": "https://openalex.org/W2086795154", "raw": "Andreas W. M. Dress and Walter Wenzel. Geometric algebra for combinatorial geometries. Adv. Math., 77(1):1–36, 1989.", "source_ref_i...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ 0.020678000524640083, -0.0006943534826859832, -0.04004359617829323, 0.02203618548810482, 0.014283843338489532, -0.028521904721856117, 0.007187703158706427, 0.04126443713903427, 0.00811096467077732, 0.006672660820186138, -0.03809024766087532, -0.014695877209305763, -0.03039894811809063, -0....
fcd9b2d1c7fdef0623b88b992f8b7de7ae6fac0b
subsection
91
144
The inner Tutte group
Recall from Theorem REF that the association \prod x_I^{e_I}\mapsto \prod X_I^{e_I} defines an isomorphism (k_M^w)^\times \rightarrow M between the units of the weak universal pasture and the Tutte group of M.Corollary 3.11 The isomorphism (k_M^w)^\times \rightarrow M restricts to an isomorphism (k_M^f)^\times \righta...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.036008622497320175, 0.004943556617945433, -0.04043341055512428, -0.006091712974011898, -0.023527666926383972, -0.007537398021668196, 0.01315993070602417, 0.01975896768271923, 0.01891978457570076, 0.058987006545066833, -0.07152899354696274, -0.045071810483932495, 0.03771750628948212, 0.0...
1d61119d19586202fb1a366232bd11fa7e8e8fd1
subsection
92
144
The inner Tutte group
By the very construction of B[T_1^{\pm 1},\cdots ,T_s^{\pm 1}], we have B[T_1^{\pm 1},\cdots ,T_s^{\pm 1}]^\times \simeq B^\times \times {\mathbb {Z}}^s.Corollary 3.12 The weak universal pasture k_M^w is isomorphic to k_M^f[T_1^{\pm 1},\cdots ,T_s^{\pm 1}] for some s\geqslant 0.The additive relations of k_M^w are gene...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.jctb.2010.04.002", "end": 1791, "openalex_id": "https://openalex.org/W2010114044", "raw": "Rudi A. Pendavingh and Stefan H. M. van Zwam. Confinement of matroid representations to subsets of partial fields. J. Combin. Theory Ser. B...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.0019947721157222986, 0.024974698200821877, -0.03167225047945976, -0.027400463819503784, -0.005454157013446093, -0.04207710549235344, 0.02457803301513195, 0.01737702079117298, 0.014005359262228012, 0.07249832898378372, -0.052573494613170624, -0.009855623356997967, 0.029994048178195953, 0...
f6df59df67f170b2317b315f957e24d9d83f4783
subsection
93
144
The inner Tutte group
Composing it with the inclusion k_M^f\rightarrow k_M^w yields the desired morphism k_M^f\rightarrow F. Thus (REF )\Rightarrow (REF ).If there is a morphism k_M^f\rightarrow F, then its image is contained in F^\textup {found}. By Corollary REF , we have k_M^w\simeq k_M^f[T_1^{\pm 1},\cdots ,T_s^{\pm 1}], and thus there ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/0001-8708(89)90013-3", "end": 1154, "openalex_id": "https://openalex.org/W2086795154", "raw": "Andreas W. M. Dress and Walter Wenzel. Geometric algebra for combinatorial geometries. Adv. Math., 77(1):1–36, 1989.", "source_ref_...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.008210567757487297, 0.008950739167630672, -0.0016119724605232477, -0.009423838928341866, 0.0012418865226209164, -0.013109438121318817, -0.0006214201566763222, 0.04721839353442192, 0.013307834044098854, 0.03308644890785217, -0.02360919676721096, -0.018603498116135597, -0.029286392033100128...
a0723add37aa124c947420816518f7b5efee280a
subsection
94
144
The inner Tutte group
Its proof is relies on Tutte's “fundamental theorem on linear subclasses” (Theorem 4.34 in ), which is significantly easier to prove than the relatively deeper parts of Tutte's homotopy theory for matroids found in and (and also exposited in ).Theorem 3.10 The inner Tutte group M^{(0)} is generated by and the elements...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.6028/jres.069b.001", "end": 246, "openalex_id": "https://openalex.org/W2324166574", "raw": "William T. Tutte. Lectures on matroids. J. Res. Nat. Bur. Standards Sect. B, 69B:1–47, 1965.", "source_ref_id": "896a7cc789c33b8b959fe84f2c...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.028874628245830536, 0.011583426967263222, -0.05585683882236481, 0.013262184336781502, -0.0010148851433768868, -0.012499112635850906, 0.00542543875053525, 0.03510129451751709, 0.014231285080313683, 0.03256789594888687, -0.052804552018642426, -0.03708527982234955, 0.002289214637130499, 0....
015773e550d2d739f680f2f5a573b72b4b627b9d
subsection
95
144
The inner Tutte group
In particular, the ordered blueprint B[T_1^{\pm 1},\cdots ,T_s^{\pm 1}] is pasteurized if and only if B is so. By the very construction of B[T_1^{\pm 1},\cdots ,T_s^{\pm 1}], we have B[T_1^{\pm 1},\cdots ,T_s^{\pm 1}]^\times \simeq B^\times \times {\mathbb {Z}}^s.Corollary 3.12 The weak universal pasture k_M^w is isom...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/j.jctb.2010.04.002", "end": 1902, "openalex_id": "https://openalex.org/W2010114044", "raw": "Rudi A. Pendavingh and Stefan H. M. van Zwam. Confinement of matroid representations to subsets of partial fields. J. Combin. Theory Ser. B...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.01881302148103714, 0.01194695569574833, -0.019759012386202812, -0.038266874849796295, -0.01543339155614376, -0.045529648661613464, 0.01660062186419964, 0.003940359223634005, 0.007583188824355602, 0.07525208592414856, -0.03979266807436943, -0.03265196084976196, 0.056698448956012726, 0.02...
870351d69fccc870551a6295c448048c69ca1d50
subsection
96
144
The inner Tutte group
Thus (REF )\Rightarrow (REF ).If M is weakly representable over F, then there exists a morphism k_M^w\rightarrow F by Proposition REF . Composing it with the inclusion k_M^f\rightarrow k_M^w yields the desired morphism k_M^f\rightarrow F. Thus (REF )\Rightarrow (REF ).If there is a morphism k_M^f\rightarrow F, then its...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.02318977378308773, 0.013265466317534447, 0.009138601832091808, -0.024501826614141464, -0.016248097643256187, -0.024059390649199486, -0.0024867982137948275, 0.04570826515555382, 0.021420028060674667, 0.041283901780843735, -0.006064430810511112, -0.024181442335247993, -0.003749267663806677,...
e31dfaa77d1aad0a8645fcf61dcbbad93fcd39f9
subsection
97
144
Rescaling classes
Let B be a pasteurized ordered blueprint and T(B) the set of functions t:E\rightarrow B^\times , which comes with the structure of an abelian group with respect to the product t\cdot t^{\prime }(i)=t(i)\cdot t^{\prime }(i). For a subset I of E, we define t_I=\prod _{i\in I}t(i). For t\in T(B) and a weak Grassmann-Plück...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.48550/arxiv.1504.07109", "end": 1650, "openalex_id": "https://openalex.org/W2798840515", "raw": "Emanuele Delucchi, Linard Hoessly, and Elia Saini. Realization spaces of matroids over hyperfields. Preprint, arXiv:1504.07109v3, 2015.", ...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.02872498333454132, -0.021612420678138733, -0.0464300736784935, 0.005040608812123537, 0.003699371824041009, -0.01301171537488699, 0.022406097501516342, 0.0473153293132782, 0.006059414707124233, 0.0437743104994297, -0.057846806943416595, -0.022283993661403656, 0.02048295922577381, 0.00803...
14f28e68d5eb9365550da39ffea0cbaaa126d528
subsection
98
144
Rescaling classes
Equivalence of representations A and A^{\prime }, in the sense of , is defined in terms of realizations as incidence geometries inside {\mathbb {P}}^{r-1}(k): A and A^{\prime } are said to be equivalent if there is an automorphism of {\mathbb {P}}^{r-1}(k) (as an incidence geometry) which identifies the respective real...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1093/acprof:oso/9780198566946.001.0001", "end": 350, "openalex_id": "https://openalex.org/W4231868828", "raw": "James G. Oxley. Matroid theory. Oxford Science Publications. The Clarendon Press, Oxford University Press, New York, 1992.", ...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.003535833675414324, -0.026623643934726715, -0.021207373589277267, -0.018689950928092003, -0.011892911978065968, 0.008711805567145348, 0.04757164791226387, 0.028820667415857315, 0.04006515443325043, 0.04445919767022133, -0.022733082994818687, -0.004714444745332003, 0.028576554730534554, ...
8238b7af32512d4819a85aff5337814116b0ed9c
subsection
99
144
Rescaling classes
The action of T(B) on \operatorname{Mat}(r,E)(B) results from applying \operatorname{Hom}(\operatorname{Spec}B,-) to the morphism T\times \operatorname{Mat}(r,E)\rightarrow \operatorname{Mat}(r,E).Note that a morphism f:F\rightarrow F^{\prime } of pastures induces a map f_\ast :{\mathcal {X}}^w(F)\rightarrow {\mathcal ...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.009407833218574524, -0.025026515126228333, -0.04538344591856003, -0.009362053126096725, -0.01213938556611538, -0.004753511864691973, 0.028521070256829262, 0.029360374435782433, -0.0173659585416317, 0.040835946798324585, -0.04712309688329697, -0.01168158371001482, 0.014687817543745041, -...
84e0769f186f70b20fb3952287e226137f2a968f
subsection
100
144
Rescaling classes
Then for I_{k,l}=I\cup \lbrace i_k,i_l\rbrace , we have t_{I_{1,2}}t_{I_{3,4}}=t_{I_{2,3}}t_{I_{4,1}} and thus\operatorname{Cr}_{\Delta ^{\prime }}({\mathcal {I}}) \quad = \quad \frac{\Delta ^{\prime }_{I,1,2}\Delta ^{\prime }_{I,3,4}}{\Delta ^{\prime }_{I,2,3}\Delta ^{\prime }_{I,4,3}} \quad = \quad \frac{at_{I_{1,2}}...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/0001-8708(89)90013-3", "end": 991, "openalex_id": "https://openalex.org/W2086795154", "raw": "Andreas W. M. Dress and Walter Wenzel. Geometric algebra for combinatorial geometries. Adv. Math., 77(1):1–36, 1989.", "source_ref_i...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.009069718420505524, 0.02610309235751629, -0.009535027667880058, -0.013707555830478668, 0.00014946155715733767, 0.024333391338586807, 0.01856660656630993, 0.0431135818362236, -0.0026011555455625057, 0.02114487811923027, -0.04482226073741913, -0.03289203345775604, -0.011609850451350212, 0...
05a6d2ddbe761fc65585234d644e69205b6b224d
subsection
101
144
Rescaling classes
This establishes the claim.Thus the morphism \deg _E:M\rightarrow {\mathbb {Z}}^E is the direct sum of its restrictions to the support of the connected components of M and the rank of the cokernel is the sum of the ranks for each summand. Therefore we may assume that M is connected, and we are left to show that under t...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.04072912409901619, -0.013805190101265907, -0.02574934996664524, -0.03258330002427101, 0.014201803132891655, 0.007825483568012714, 0.019723879173398018, 0.05506821721792221, -0.005766145884990692, 0.02716800384223461, -0.05021733418107033, -0.0028315894305706024, 0.002152770757675171, 0....
1fa63e94b4b26133dae5ed9b784e7f6283473060
subsection
102
144
Rescaling classes
Since _{[\Delta ]} sends \prod x_I^{e_I} to \prod \Delta (I)^{e_I}, and similarly for _{[\Delta ^{\prime }]}, we have \operatorname{Cr}_\Delta =_{[\Delta ]}\circ \operatorname{Cr}_M^\textup {univ} and \operatorname{Cr}_{\Delta ^{\prime }}=_{[\Delta ^{\prime }]}\circ \operatorname{Cr}_M^\textup {univ}. Thus for every {\...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.049639418721199036, 0.021402614191174507, -0.02863343246281147, -0.003111997852101922, -0.0028984295204281807, 0.03343872353434563, -0.018794026225805283, 0.037313465029001236, 0.004862496629357338, 0.00445442833006382, -0.03545236960053444, -0.011738639324903488, -0.025353631004691124, ...
d5d95312464847465e1b57ec6cbb80d90098a565
subsection
103
144
Rescaling classes
Then we have\textstyle \prod \Delta (I)^{e_I} \ = \ _{[\Delta ]}\big ( \prod x_I^{e_I}\big ) \ = \ t\big (\sum e_I_I\big ) \ _{[\Delta ^{\prime }]}\big ( \prod x_I^{e_I}\big ) \ = \ \prod t_I^{e_I} \, \cdot \, \prod \Delta ^{\prime }(x_I)^{e_I} \ = \ (t.\Delta ^{\prime })(I)^{e_I}for all e_I with \sum e_I=0, where I va...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.027505120262503624, -0.016521379351615906, -0.04073137789964676, -0.02366081066429615, 0.022592946887016296, 0.0042066206224262714, 0.004591814242303371, 0.0545220747590065, 0.02344723790884018, 0.04402650147676468, -0.04893867298960686, -0.01626203954219818, -0.012951662763953209, -0.0...
11e56a246390367313a00df4774d3616bcbaa244
subsection
104
144
Rescaling classes
Then the map\begin{array}{cccc} \Phi : & {\mathcal {X}}_M^f(F) & \longrightarrow & \operatorname{Hom}(k_M^f,F) \\ & [\Delta ] & \longmapsto & _{[\Delta ]}\vert _{k_M^f} \end{array}is a bijection that is functorial in F.By Theorem REF , two Grassmann-Plücker functions \Delta and \Delta ^{\prime } that represent M are re...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.04692608863115311, -0.007379875052720308, -0.006845930591225624, -0.031243378296494484, -0.0035659861750900745, -0.06215113401412964, 0.01864228956401348, 0.016247166320681572, 0.04259351268410683, 0.05934411287307739, -0.037986334413290024, 0.006174685899168253, 0.018016811460256577, 0...
1d1ee2e7bbe0aa81cc4d2e1a06969df7094eb777
subsection
105
144
Rescaling classes
Since the image of _{[\Delta ]}^f is contained in F^\textup {found}, the rescaling class of [\Delta ] comes from a class of an F^\textup {found}-matroid [\Delta ^{\prime }] that is represented by a Grassmann-Plücker function \Delta ^{\prime }:\binom{E}{r}\rightarrow F^\textup {found}.Thus \Delta and \circ \Delta ^{\pri...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.030645953491330147, -0.022530648857355118, -0.018122145906090736, -0.03499343618750572, -0.009541585110127926, -0.0012003252049908042, 0.019373001530766487, 0.0431087426841259, 0.014850092120468616, 0.06931568682193756, -0.033620547503232956, -0.007493690587580204, -0.004732656292617321, ...
43067ed2c88c09a11ac2c46a2189ab8e93a578d3
subsection
106
144
Rescaling classes
Thus there exists a GIT quotient X^f_M=X^w_M/T^{\prime } as a scheme, and this quotient satisfies X^f_M(k)={\mathcal {X}}^f_M(k) for every field k.Let B be a pasteurized ordered blueprint and T(B) the set of functions t:E\rightarrow B^\times , which comes with the structure of an abelian group with respect to the produ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.48550/arxiv.1504.07109", "end": 1797, "openalex_id": "https://openalex.org/W2798840515", "raw": "Emanuele Delucchi, Linard Hoessly, and Elia Saini. Realization spaces of matroids over hyperfields. Preprint, arXiv:1504.07109v3, 2015.", ...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.037392206490039825, -0.022801615297794342, -0.04685472697019577, -0.014750844798982143, 0.012812554836273193, -0.005578306969255209, 0.03345457836985588, 0.047587309032678604, 0.009393838234245777, 0.04233713820576668, -0.05103654786944389, -0.01585734821856022, 0.0057881614193320274, 0...
c1d7bf40cce8ba5c8cfe839e434c8a643c7fa957
subsection
107
144
Rescaling classes
Equivalence of representations A and A^{\prime }, in the sense of , is defined in terms of realizations as incidence geometries inside {\mathbb {P}}^{r-1}(k): A and A^{\prime } are said to be equivalent if there is an automorphism of {\mathbb {P}}^{r-1}(k) (as an incidence geometry) which identifies the respective real...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1093/acprof:oso/9780198566946.001.0001", "end": 350, "openalex_id": "https://openalex.org/W4231868828", "raw": "James G. Oxley. Matroid theory. Oxford Science Publications. The Clarendon Press, Oxford University Press, New York, 1992.", ...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.003535833675414324, -0.026623643934726715, -0.021207373589277267, -0.018689950928092003, -0.011892911978065968, 0.008711805567145348, 0.04757164791226387, 0.028820667415857315, 0.04006515443325043, 0.04445919767022133, -0.022733082994818687, -0.004714444745332003, 0.028576554730534554, ...
2869180548326fcff87b3b3b52fe4981cdbe97a3
subsection
108
144
Rescaling classes
The action of T(B) on \operatorname{Mat}(r,E)(B) results from applying \operatorname{Hom}(\operatorname{Spec}B,-) to the morphism T\times \operatorname{Mat}(r,E)\rightarrow \operatorname{Mat}(r,E).Note that a morphism f:F\rightarrow F^{\prime } of pastures induces a map f_\ast :{\mathcal {X}}^w(F)\rightarrow {\mathcal ...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.009407833218574524, -0.025026515126228333, -0.04538344591856003, -0.009362053126096725, -0.01213938556611538, -0.004753511864691973, 0.028521070256829262, 0.029360374435782433, -0.0173659585416317, 0.040835946798324585, -0.04712309688329697, -0.01168158371001482, 0.014687817543745041, -...
e0374285ea2df2fbdf433c7ad58a1c14c99368d0
subsection
109
144
Rescaling classes
Then for I_{k,l}=I\cup \lbrace i_k,i_l\rbrace , we have t_{I_{1,2}}t_{I_{3,4}}=t_{I_{2,3}}t_{I_{4,1}} and thus\operatorname{Cr}_{\Delta ^{\prime }}({\mathcal {I}}) \quad = \quad \frac{\Delta ^{\prime }_{I,1,2}\Delta ^{\prime }_{I,3,4}}{\Delta ^{\prime }_{I,2,3}\Delta ^{\prime }_{I,4,3}} \quad = \quad \frac{at_{I_{1,2}}...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1016/0001-8708(89)90013-3", "end": 991, "openalex_id": "https://openalex.org/W2086795154", "raw": "Andreas W. M. Dress and Walter Wenzel. Geometric algebra for combinatorial geometries. Adv. Math., 77(1):1–36, 1989.", "source_ref_i...
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.009069718420505524, 0.02610309235751629, -0.009535027667880058, -0.013707555830478668, 0.00014946155715733767, 0.024333391338586807, 0.01856660656630993, 0.0431135818362236, -0.0026011555455625057, 0.02114487811923027, -0.04482226073741913, -0.03289203345775604, -0.011609850451350212, 0...
86d64272743d66741ddbad7d23b53e809d42209b
subsection
110
144
Rescaling classes
This establishes the claim.Thus the morphism \deg _E:M\rightarrow {\mathbb {Z}}^E is the direct sum of its restrictions to the support of the connected components of M and the rank of the cokernel is the sum of the ranks for each summand. Therefore we may assume that M is connected, and we are left to show that under t...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.04072912409901619, -0.013805190101265907, -0.02574934996664524, -0.03258330002427101, 0.014201803132891655, 0.007825483568012714, 0.019723879173398018, 0.05506821721792221, -0.005766145884990692, 0.02716800384223461, -0.05021733418107033, -0.0028315894305706024, 0.002152770757675171, 0....
2179daaeef6e799e4126392fc75836c80ddbde8e
subsection
111
144
Rescaling classes
Since _{[\Delta ]} sends \prod x_I^{e_I} to \prod \Delta (I)^{e_I}, and similarly for _{[\Delta ^{\prime }]}, we have \operatorname{Cr}_\Delta =_{[\Delta ]}\circ \operatorname{Cr}_M^\textup {univ} and \operatorname{Cr}_{\Delta ^{\prime }}=_{[\Delta ^{\prime }]}\circ \operatorname{Cr}_M^\textup {univ}. Thus for every {\...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.049639418721199036, 0.021402614191174507, -0.02863343246281147, -0.003111997852101922, -0.0028984295204281807, 0.03343872353434563, -0.018794026225805283, 0.037313465029001236, 0.004862496629357338, 0.00445442833006382, -0.03545236960053444, -0.011738639324903488, -0.025353631004691124, ...
4739920bfa31161ff8cb881687f3a1afe55b570a
subsection
112
144
Rescaling classes
Then we have\textstyle \prod \Delta (I)^{e_I} \ = \ _{[\Delta ]}\big ( \prod x_I^{e_I}\big ) \ = \ t\big (\sum e_I_I\big ) \ _{[\Delta ^{\prime }]}\big ( \prod x_I^{e_I}\big ) \ = \ \prod t_I^{e_I} \, \cdot \, \prod \Delta ^{\prime }(x_I)^{e_I} \ = \ (t.\Delta ^{\prime })(I)^{e_I}for all e_I with \sum e_I=0, where I va...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.027505120262503624, -0.016521379351615906, -0.04073137789964676, -0.02366081066429615, 0.022592946887016296, 0.0042066206224262714, 0.004591814242303371, 0.0545220747590065, 0.02344723790884018, 0.04402650147676468, -0.04893867298960686, -0.01626203954219818, -0.012951662763953209, -0.0...
e7faeac1f09c8d0f72c15c1c9ba681ab0c2a9411
subsection
113
144
Rescaling classes
Then the map\begin{array}{cccc} \Phi : & {\mathcal {X}}_M^f(F) & \longrightarrow & \operatorname{Hom}(k_M^f,F) \\ & [\Delta ] & \longmapsto & _{[\Delta ]}\vert _{k_M^f} \end{array}is a bijection that is functorial in F.By Theorem REF , two Grassmann-Plücker functions \Delta and \Delta ^{\prime } that represent M are re...
{ "cite_spans": [] }
1809.03542
The moduli space of matroids
[ "Matthew Baker", "Oliver Lorscheid" ]
[ "math.AG" ]
2,018
en
Mathematics
[ -0.04692608863115311, -0.007379875052720308, -0.006845930591225624, -0.031243378296494484, -0.0035659861750900745, -0.06215113401412964, 0.01864228956401348, 0.016247166320681572, 0.04259351268410683, 0.05934411287307739, -0.037986334413290024, 0.006174685899168253, 0.018016811460256577, 0...