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600
Nuclear and Trace Ideals in Tensored *-Categories
math.CT
We generalize the notion of nuclear maps from functional analysis by defining nuclear ideals in tensored *-categories. The motivation for this study came from attempts to generalize the structure of the category of relations to handle what might be called ``probabilistic relations''. The compact closed structure associ...
math
601
Basic Bicategories
math.CT
A concise guide to very basic bicategory theory, from the definition of a bicategory to the coherence theorem.
math
602
Applications of Rewriting Systems and Groebner Bases to Computing Kan Extensions and Identities Among Relations
math.CT
This thesis concentrates on the development and application of rewriting and Groebner basis methods to a range of combinatorial problems. Chapter Two contains the most important result, which is the application of Knuth-Bendix procedures to Kan extensions, showing how rewriting provides a useful method for attempting...
math
603
K-Theory for Triangulated Categories III(A): The Theorem of the Heart
math.CT
This is the fourth installment of a series. The main point of the entire series is the following: given a triangulated category T, it is possible to attach to it a K-theory space.
math
604
fc-multicategories
math.CT
fc-multicategories are a very general kind of two-dimensional structure, encompassing bicategories, monoidal categories, double categories and ordinary multicategories. We define them and explain how they provide a natural setting for two familiar categorical ideas. The first is the bimodules construction, traditionall...
math
605
On Ideals and Homology in Additive Categories
math.CT
Ideals are used to define homological functors for additive categories. In abelian categories the ideals corresponding to the usual universal objects are principal, and the construction reduces, in a choice dependent way, to homology groups. Applications are considered: derived categories and functors.
math
606
Grothendieck Categories
math.CT
The general theory of Grothendieck categories is presented. We systemize the principle methods and results of the theory, showing how these results can be used for studying rings and modules.
math
607
Algebraic duality for partially ordered sets
math.CT
For an arbitrary partially ordered set $P$ its {\em dual} $P^*$ is built as the collection of all monotone mappings $P\to\2$ where $\2=\{0,1\}$ with $0<1$. The set of mappings $P^*$ is proved to be a complete lattice with respect to the pointwise partial order. The {\em second dual} $P^{**}$ is built as the collection ...
math
608
Coherence in Substructural Categories
math.CT
It is proved that MacLane's coherence results for monoidal and symmetric monoidal categories can be extended to some other categories with multiplication; namely, to relevant, affine and cartesian categories. All results are formulated in terms of natural transformations equipped with ``graphs'' (g-natural transformati...
math
609
From Coherent Structures to Universal Properties
math.CT
Given a 2-category $\twocat{K}$ admitting a calculus of bimodules, and a 2-monad T on it compatible with such calculus, we construct a 2-category $\twocat{L}$ with a 2-monad S on it such that: (1)S has the adjoint-pseudo-algebra property. (2)The 2-categories of pseudo-algebras of S and T are equivalent. Thus, coherent ...
math
610
On the Galois Theory of Grothendieck
math.CT
In this paper we deal with Grothendieck's interpretation of Artin's interpretation of Galois's Galois Theory (and its natural relation with the fundamental group and the theory of coverings) as he developed it in Expose V, section 4, ``Conditions axiomatiques d'une theorie de Galois'' in the SGA1 1960/61. This is a b...
math
611
A relative Yoneda Lemma (manuscript)
math.CT
We construct set-valued right Kan-extensions via a relative Yoneda Lemma.
math
612
Localic Galois Theory
math.CT
In Proposition I of "Memoire sur les conditions de resolubilite des equations par radicaux", Galois established that any intermediate extension of the splitting field of a polynomial with rational coefficients is the fixed field of its galois group. We first state and prove the (dual) categorical interpretation of of...
math
613
On the monad of proper factorisation systems in categories
math.CT
It is known that factorisation systems in categories can be viewed as unitary pseudo algebras for the "squaring" monad in Cat. We show in this note that an analogous fact holds for proper (i.e., epi-mono) factorisation systems and a suitable quotient of the former monad, deriving from a construct introduced by P. Fre...
math
614
On Ext in the Category of Functors to Preabelian Category
math.CT
The work is devoted to the extension groups in the category of functors from a small category to an additive category with an Abelian structure in the sense of Heller. It is constructed a spectral sequence which converges to the extension group. Example for diagrams of locally convex spaces is given.
math
615
n-Categories Admissible by n-graph
math.CT
The concept of n-categories and related subject is considered. An n-category is described as an n-graph with a composition. A new definition of operad is presented. Some illustrative examples are given.
math
616
Calculating limits and colimits in pro-categories
math.CT
We present some constructions of limits and colimits in pro-categories. These are critical tools in several applications. In particular, certain technical arguments concerning strict pro-maps are essential for a theorem about \'etale homotopy types. Also, we show that cofiltered limits in pro-categories commute with fi...
math
617
Flows in Graphs and Homology of Free Categories
math.CT
We introduce the notion of a generalized flow on a graph with coefficients in a R-representation and show that the module of flows is isomorphic to the first derived functor of the colimit. We generalize Kirchhoff's laws and build an exact sequence for calculating the module of flows on the union of graphs.
math
618
Cohomologie non abelienne d'ordre superieur et applications
math.CT
In this paper we propose a higher non abelian cohomology theory without using the notion of n-category. We use this to study compositions series of affine manifolds and cohomology of manifolds.
math
619
Structures in higher-dimensional category theory
math.CT
This paper, written in 1998, aims to clarify various higher categorical structures, mostly through the theory of generalized operads and multicategories. Chapters I and II, which cover this theory and its application to give a definition of weak n-category, are largely superseded by my thesis (math.CT/0011106), but Cha...
math
620
Some properties of the theory of n-categories
math.CT
Let $L_n$ denote the Dwyer-Kan localization of the category of weak n-categories divided by the n-equivalences. We propose a list of properties that this simplicial category is likely to have, and conjecture that these properties characterize $L_n$ up to equivalence. We show, using these properties, how to obtain the m...
math
621
On the Structure of Modular Categories
math.CT
For a braided tensor category C and a subcategory K there is a notion of centralizer C_C(K), which is a full tensor subcategory of C. A pre-modular tensor category is known to be modular in the sense of Turaev iff the center Z_2(C):=C_C(C) (not to be confused with the center Z_1 of a tensor category, related to the qua...
math
622
Pushout stability of embeddings, injectivity and categories of algebras
math.CT
In several familiar subcategories of the category ${\mathbb T}$ of topological spaces and continuous maps, embeddings are not pushout-stable. But, an interesting feature, capturable in many categories, namely in categories $\mathcal{B}$ of topological spaces, is the following: For $\mathcal{M}$ the class of all embeddi...
math
623
Generalized enrichment of categories
math.CT
We define the phrase `category enriched in an fc-multicategory' and explore some examples. An fc-multicategory is a very general kind of 2-dimensional structure, special cases of which are double categories, bicategories, monoidal categories and ordinary multicategories. Enrichment in an fc-multicategory extends the (m...
math
624
On Regular Closure Operators and Cowellpowered Subcategories
math.CT
Many Properties of a category X, as for instance the existence of an adjoint or a factorization system, are a consequence of the cowellpoweredness of X. In the absence of cowellpoweredness, for general results, fairly strong assumption on the category are needed. This paper provides a number of novel and useful observa...
math
625
The omega-Categories Associated With Products of Infinite-Dimensional Globes
math.CT
This thesis studies the omega-categories associated with products of infinite-dimensional globes.
math
626
On the representation theory of Galois and Atomic Topoi
math.CT
We elaborate on the representation theorems of topoi as topoi of discrete actions of various kinds of localic groups and groupoids. We introduce the concept of "proessential point" and use it to give a new characterization of pointed Galois topoi. We establish a hierarchy of connected topoi: [1. essentially pointed A...
math
627
Computads and slices of operads
math.CT
For a given $\omega$-operad $A$ on globular sets we introduce a sequence of symmetric operads on $Set$ called slices of $A$ and show how the connected limit preserving properties of slices are related to the property of the category of $n$-computads of $A$ being a presheaf topos.
math
628
Galois extensions of braided tensor categories and braided crossed G-categories
math.CT
We show that the author's notion of Galois extensions of braided tensor categories [22], see also [3], gives rise to braided crossed G-categories, recently introduced for the purposes of 3-manifold topology [31]. The Galois extensions C \rtimes S are studied in detail, and we determine for which g in G non-trivial obje...
math
629
Group Objects and Internal Categories
math.CT
Algebraic structures such as monoids, groups, and categories can be formulated within a category using commutative diagrams. In many common categories these reduce to familiar cases. In particular, group objects in Grp are abelian groups, while internal categories in Grp are equivalent both to group objects in Cat and ...
math
630
Remarks on 2-Groups
math.CT
A 2-group is a `categorified' version of a group, in which the underlying set G has been replaced by a category and the multiplication map m: G x G -> G has been replaced by a functor. A number of precise definitions of this notion have already been explored, but a full treatment of their relationships is difficult to ...
math
631
Non abelian cohomology: the point of view of gerbed tower
math.CT
In this paper we define a notion of gerbed tower, and use this notion to give a geometric representation of cohomological classes.
math
632
Paracategories I: internal parategories and saturated partial algebras
math.CT
Based on the monoid classifier, we give an alternative axiomatization of Freyd's paracategories, which can be interpreted in any bicategory of partial maps. Assuming furthermore a free-monoid monad T in our ambient category, and coequalisers satisfying some exactness conditions, we give an abstract envelope constructio...
math
633
Some calculus with extensive quantities: wave equation
math.CT
We take some first steps in providing a synthetic theory of distributions. In particular, we are interested in the use of distribution theory as foundation, not just as tool, in the study of the wave equation.
math
634
The monoidal centre as a limit
math.CT
The centre of a monoidal category is a braided monoidal category. Monoidal categories are monoidal objects (or pseudomonoids) in the monoidal bicategory of categories. This paper provides a universal construction in a braided monoidal bicategory that produces a braided monoidal object from any monoidal object. Some pro...
math
635
Weak n-categories: opetopic and multitopic foundations
math.CT
We generalise the concepts introduced by Baez and Dolan to define opetopes constructed from symmetric operads with a category, rather than a set, of objects. We describe the category of 1-level generalised multicategories, a special case of the concept introduced by Hermida, Makkai and Power, and exhibit a full embeddi...
math
636
Weak n-categories: comparing opetopic foundations
math.CT
We define the category of tidy symmetric multicategories. We construct for each tidy symmetric multicategory Q a cartesian monad (E_Q,T_Q) and extend this assignation to a functor. We exhibit a relationship between the slice construction on symmetric multicategories, and the `free operad' monad construction on suitable...
math
637
The category of opetopes and the category of opetopic sets
math.CT
We give an explicit construction of the category Opetope of opetopes. We prove that the category of opetopic sets is equivalent to the category of presheaves over Opetope.
math
638
Opetopic bicategories: comparison with the classical theory
math.CT
We continue our previous modifications of the Baez-Dolan theory of opetopes to modify the Baez-Dolan definition of universality, and thereby the category of opetopic n-categories and lax functors. For the case n=2 we exhibit an equivalence between this category and the category of bicategories and lax functors. We exam...
math
639
An alternative characterisation of universal cells in opetopic n-categories
math.CT
We address the fact that composition in an opetopic weak n-category is in general not unique and hence is not a well-defined operation. We define composition with a given k-cell in an n-category by a span of (n-k)-categories. We characterise such a cell as universal if its composition span gives an equivalence of (n-k)...
math
640
A relationship between trees and Kelly-Mac Lane graphs
math.CT
We give a precise description of combed trees in terms of Kelly-Mac Lane graphs. We show that any combed tree is uniquely expressed as an allowable Kelly-Mac Lane graph of a certain shape. Conversely, we show that any such Kelly-Mac Lane graph uniquely defines a combed tree.
math
641
The theory of opetopes via Kelly-Mac Lane graphs
math.CT
This paper follows from two earlier works. In the first we gave an explicit construction of opetopes, the underlying cell shapes in the theory of opetopic n-categories; at the heart of this construction is the use of certain trees. In the second we gave a description of trees using Kelly-Mac Lane graphs. In the present...
math
642
Category Theory and Higher Dimensional Algebra: potential descriptive tools in neuroscience
math.CT
We explain the notion of colimit in category theory as a potential tool for describing structures and their communication, and the notion of higher dimensional algebra as a potential yoga for dealing with processes and processes of processes.
math
643
A Guided Tour in the Topos of Graphs
math.CT
In this paper we survey the fundamental constructions of a presheaf topos in the case of the elementary topos of graphs. We prove that the transition graphs of nondeterministic automata (a.k.a. labelled transition systems) are the separated presheaves for the double negation topology, and obtain as an application that ...
math
644
Strengthening track theories
math.CT
Using cohomology of categories with coefficients in natural systems it is proved that a groupoid enrichad category with pseudoproducts is pseudoequivalent to one with strict products.
math
645
A generalization and a new proof of Plotkin's reduction theorem
math.CT
It is known that Plotkin's reduction theorem is very important for his theory of universal algebraic geometry [arXiv:math. GM/0210187], [arXiv:math. GM/0210194]. It turns out that this theorem can be generalized to arbitrary categories containing two special objects and in this case its proof becomes considerable more ...
math
646
Flatness, preorders and general metric spaces
math.CT
This paper studies a general notion of flatness in the enriched context: P-flatness where the parameter P stands for a class of presheaves. One obtains a completion of a category A by considering the category Flat_P(A) of P-flat presheaves over A. This completion is related to the free cocompletion of A under a class o...
math
647
Grothendieck categories and support conditions
math.CT
We give examples of pairs (G1,G2) where G1 is a Grothendieck category and G2 a full Grothendieck subcategory of G1, the inclusion G2 --> G1 being denoted i, for which R^+i : D^+G2 --> D^+G1 (or even Ri : DG2 --> DG1) is a full embedding. This yields generalizations of some results of Bernstein and Lunts, and of Cline, ...
math
648
Monad interleaving: a construction of the operad for Leinster's weak $ω$-categories
math.CT
We show how to "interleave" the monad for operads and the monad for contractions on the category \coll of collections, to construct the monad for the operads-with-contraction of Leinster. We first decompose the adjunction for operads and the adjunction for contractions into a chain of adjunctions each of which acts on ...
math
649
Free ${A}_\infty$-categories
math.CT
For a differential graded k-quiver Q we define the free A-infinity-category FQ generated by Q. The main result is that for an arbitrary A-infinity-category A the restriction A-infinity-functor A_\infty(FQ,A) -> A_1(Q,A) is an equivalence, where objects of the last A-infinity-category are morphisms of differential grade...
math
650
Homotopical structures in categories
math.CT
In this paper is presented a new approach to the axiomatic homotopy theory in categories, which offers a simpler and more useful answer to this old question: how two objects in a category (without any topological feature) can be deformed each in other?
math
651
A duality Hopf algebra for holomorphic N=1 special geometries
math.CT
We find a self-dual noncommutative and noncocommutative Hopf algebra acting as a universal symmetry on the modules over inner Frobenius algebras of modular categories (as used in two dimensional boundary conformal field theory) similar to the Grothendieck-Teichmueller group GT as introduced by Drinfeld as a universal s...
math
652
Flatness, accessibility and metric spaces
math.CT
This paper studies a notion of parameterized flatness in the enriched context: p-flatness where the parameter p stands for a class of presheaves. One obtains a completion of a category A by considering the category F_p(A) of p-flat presheaves over A. The completion is related to the free cocompletion under a class of c...
math
653
Omega-categories and chain complexes
math.CT
There are several ways to construct omega-categories from combinatorial objects such as pasting schemes or parity complexes. We make these constructions into a functor on a category of chain complexes with additional structure, which we call augmented directed complexes. This functor from augmented directed complexes t...
math
654
Les groupements
math.CT
Neocategories, semicategories, precategories are well-known generalizations of categories. But they all suppose that sources and targets of morphisms fulfilled identity conditions. Here we intend to suppress those conditions. In doing this we get at the construction of a simple framework which seems appropiate to study...
math
655
Tours de torseurs, geometrie differentielle des suites de fibres principaux, et theorie des cordes
math.CT
In this paper we interpret cohomological class using the notion of tower of torsors, we apply our construction to string theory.
math
656
The Chu construction for complete atomistic coatomistic lattices
math.CT
The Chu construction is used to define a *-autonomous structure on a category of complete atomistic coatomistic lattices. This construction leads to a new tensor product that is compared with a certain number of other existing tensor products.
math
657
A strict totally coordinatized version of Kapranov and Voevodsky's 2-category {\bf 2Vect}
math.CT
We give a concrete description of a strict totally coordinatized version of Kapranov and Voevodsky's 2-category of finite dimensional 2-vector spaces. In particular, we give explicit formulas for composition of 1-morphisms and the two compositions between 2-morphisms
math
658
A Full and faithful Nerve for 2-categories
math.CT
The notion of geometric nerve of a 2-category (Street, \cite{refstreet}) provides a full and faithful functor if regarded as defined on the category of 2-categories and lax 2-functors. Furthermore, lax 2-natural transformations between lax 2-functors give rise to homotopies between the corresponding simplicial maps. Th...
math
659
State monads and their algebras
math.CT
State monads in cartesian closed categories are those defined by the familiar adjunction between product and exponential. We investigate the structure of their algebras, and show that the exponential functor is monadic provided the base category is sufficiently regular, and the exponent is a non-empty object.
math
660
Enlargements of Categories
math.CT
In order to apply nonstandard methods to modern algebraic geometry, as a first step in this paper we study the applications of nonstandard constructions to category theory. It turns out that many categorial properties are well behaved under enlargements.
math
661
Non-well-founded trees in categories
math.CT
Non-well-founded trees are used in mathematics and computer science, for modelling non-well-founded sets, as well as non-terminating processes or infinite data-structures. Categorically, they arise as final coalgebras for polynomial endofunctors, which we call M-types. In order to reason about trees, we need the notion...
math
662
Categorical structures enriched in a quantaloid: categories, distributors and functors
math.CT
We thoroughly treat several familiar and less familiar definitions and results concerning categories, functors and distributors enriched in a base quantaloid Q. In analogy with V-category theory we discuss such things as adjoint functors, (pointwise) left Kan extensions, weighted (co)limits, presheaves and free (co)com...
math
663
Categorical structures enriched in a quantaloid: regular presheaves, regular semicategories
math.CT
We study presheaves on semicategories enriched in a quantaloid: this gives rise to the notion of regular presheaf. A semicategory is regular when its representable presheaves are regular, and its regular presheaves then constitute an essential (co)localization of the category of all of its presheaves. The notion of reg...
math
664
Categorical structures enriched in a quantaloid: orders and ideals over a base quantaloid
math.CT
Applying (enriched) categorical structures we define the notion of ordered sheaf on a quantaloid Q, which we call `Q-order'. This requires a theory of semicategories enriched in the quantaloid Q, that admit a suitable Cauchy completion. There is a quantaloid Idl(Q) of Q-orders and ideal relations, and a locally ordered...
math
665
Towards an axiomatization of the theory of higher categories
math.CT
We define a notion of "theory of (1,infty)-categories", and we prove that such a theory is unique up to equivalence.
math
666
Categorical non abelian cohomology, and the Schreier theory of groupoids
math.CT
By regarding the classical non abelian cohomology of groups from a 2-dimensional categorical viewpoint, we are led to a non abelian cohomology of groupoids which continues to satisfy classification, interpretation and representation theorems generalizing the classical ones. This categorical approach is based on the fac...
math
667
Higher gauge theory I: 2-Bundles
math.CT
I categorify the definition of fibre bundle, replacing smooth manifolds with differentiable categories, Lie groups with coherent Lie 2-groups, and bundles with a suitable notion of 2-bundle. To link this with previous work, I show that certain 2-categories of principal 2-bundles are equivalent to certain 2-categories o...
math
668
Categorical structures enriched in a quantaloid: tensored and cotensored categories
math.CT
Our subject is that of categories, functors and distributors enriched in a base quantaloid Q. We show how cocomplete Q-categories are precisely those which are tensored and conically cocomplete, or alternatively, those which are tensored, cotensored and order-cocomplete. Bearing this in mind, we analyze how Sup-valued ...
math
669
Covering groupoids
math.CT
Topos properties of the category of covering groupoids over a fixed groupoid are discussed. A classification result for connected covering groupoids over a fixed groupoid analogous to the fundamental theorem of Galois theory is given.
math
670
On the $\mathbb{Z} D_\infty$-category
math.CT
In this paper we give a direct proof of the properties of the $\ZZ D_\infty$ category which was introduced in the classification of noetherian, hereditary categories with Serre duality by Idun Reiten and the author.
math
671
Notes on enriched categories with colimits of some class
math.CT
Given a class Phi of weights, we study the following classes: Phi^+ of Phi-flat weights which are the psi for which psi-colimits commute in the base V with limits with weights in Phi; and Phi^-, dually defined, of weights psi for which psi-limits commute in the base V with colimits with weights in Phi. We show that bot...
math
672
Towards "dynamic domains": totally continuous cocomplete Q-categories
math.CT
It is common practice in both theoretical computer science and theoretical physics to describe the (static) logic of a system by means of a complete lattice. When formalizing the dynamics of such a system, the updates of that system organize themselves quite naturally in a quantale, or more generally, a quantaloid. In ...
math
673
Cohomology of the Grothendieck construction
math.CT
We consider cohomology of small categories with coefficients in a natural system in the sense of Baues and Wirsching. For any funtor L: K -> CAT, we construct a spectral sequence abutting to the cohomology of the Grothendieck construction of L in terms of the cohomology of K and of L(k), for k an object in K.
math
674
Quadratic categories, Koszul resolutions and operads
math.CT
A quadratic algebra is a homogeneous algebra generated by its elements of degree 1. Manin has endowed the category of quadratic algebras with two tensor products. These structures have been adapted to operads by Ginsburg and Kapranov. Berger has defined such tensor products for n-homogeneous algebras. The purpose of th...
math
675
Generalized Brown representability in homotopy categories
math.CT
We show that the homotopy category of a combinatorial stable model category $\ck$ is well generated. It means that each object $K$ of $\Ho(\ck)$ is an iterated weak colimit of $\lambda$-compact objects for some cardinal $\lambda$. A natural question is whether each $K$ is a weak colimit of $\lambda$-compact objects. We...
math
676
Files for Gabriel-Zisman localization
math.CT
This preprint contains the Coq proof files for Gabriel-Zisman localization, bundled with the source. The text of this preprint consists of the definitions and lemma statements of the main files, with proofs removed. See the other preprint ``Explaining GZ localization to the computer'' for explanation and discussion.
math
677
On the non additivity of the trace in derived categories
math.CT
In this note we provide an example of an endomorphism of a short exact sequence of perfect complexes, with the trace of the middle map not equal to the sum of the traces of the two other ones. The point is that the squares involved are commutative only up to homotopy. In view of this example I have found in 1968, Delig...
math
678
Weak identity arrows in higher categories
math.CT
There are a dozen definitions of weak higher categories, all of which loosen the notion of composition of arrows. A new approach is presented here, where instead the notion of identity arrow is weakened -- these are tentatively called fair categories. The approach is simplicial in spirit, but the usual simplicial categ...
math
679
Elementary remarks on units in monoidal categories
math.CT
We explore an alternative definition of unit in a monoidal category originally due to Saavedra: a Saavedra unit is a cancellative idempotent (in a 1-categorical sense). This notion is more economical than the usual notion in terms of left-right constraints, and is motivated by higher category theory. To start, we descr...
math
680
On lifting stable diagrams in Frobenius categories
math.CT
Suppose given a Frobenius category E, i.e. an exact category with a big enough subcategory B of bijectives. Let_E_ := E/B denote its classical stable category. For example, we may take E to be the category of complexes C(A) with entries in an additive category A, in which case_E_ is the homotopy category of complexes K...
math
681
Notes on enriched categories with colimits of some class (completed version)
math.CT
The paper is in essence a survey of categories having $\phi$-weighted colimits for all the weights $\phi$ in some class $\Phi$. We introduce the class $\Phi^+$ of {\em $\Phi$-flat} weights which are those $\psi$ for which $\psi$-colimits commute in the base $\V$ with limits having weights in $\Phi$; and the class $\Phi...
math
682
Lambda-presentable morphisms, injectivity and (weak) factorization systems
math.CT
We show that in a locally lambda-presentable category, every lambda(m)-injectivity class (i.e., the class of all the objects injective with respect to some class of lambda-presentable morphisms) is a weakly reflective subcategory determined by a functorial weak factorization system cofibrantly generated by a class of l...
math
683
Identity and Categorification
math.CT
In the paper I check approaches to identity in mathematics by Plato, Frege, and Geach against Category theory.
math
684
Cryptography and Encryption
math.CT
In cryptography, encryption is the process of obscuring information to make it unreadable without special knowledge. This is usually done for secrecy, and typically for confidential communications. Encryption can also be used for authentication, digital signatures, digital cash e.t.c. In this paper we are going to exam...
math
685
Commutation Structures
math.CT
For a fixed object X in a monoidal category, an X-commutation structure on an object A is just a map from XA to AX. We study aspects of such structure in case A has a dual.
math
686
Notes on 2-groupoids, 2-groups and crossed-modules
math.CT
This paper contains some basic results on 2-groupoids, with special emphasis on computing derived mapping 2-groupoids between 2-groupoids and proving their invariance under strictification. Some of the results proven here are presumably folklore (but do not appear in the literature to the author's knowledge) and some o...
math
687
Bipolar spaces
math.CT
Some basic features of the simultaneous inclusion of discrete fibrations and discrete opfibrations on a category A in the category of categories over A are studied; in particular, the reflections and the coreflections of the latter in the former are considered, along with a negation-complement operator which, applied t...
math
688
Quadratic categories and Koszul resolutions
math.CT
In this paper we define quadratic categories and their representations.
math
689
Orientals
math.CT
The orientals or oriented simplexes are a family of strict omega-categories constructed by Ross Street. We show that the category of orientals is isomorphic to a subcategory of the category of chain complexes. This leads to a very simple combinatorial description of the morphisms between orientals. We also show that th...
math
690
Thin fillers in the cubical nerves of omega-categories
math.CT
It is shown that the cubical nerve of a strict omega-category is a sequence of sets with cubical face operations and distinguished subclasses of thin elements satisfying certain thin filler conditions. It is also shown that a sequence of this type is the cubical nerve of a strict omega-category unique up to isomorphism...
math
691
Categories, norms and weights
math.CT
The well-known Lawvere category R of extended real positive numbers comes with a monoidal closed structure where the tensor product is the sum. But R has another such structure, given by multiplication, which is *-autonomous. Normed sets, with a norm in R, inherit thus two symmetric monoidal closed structures, and ca...
math
692
Universal coefficient theorem in triangulated categories
math.CT
Let T be a triangulated category, A a graded abelian category and h: T -> A a homology theory on T with values in A. If the functor h reflects isomorphisms, is full and is such that for any object x in A there is an object X in T with an isomorphism between h(X) and x, we prove that A is a hereditary abelian category a...
math
693
Finite Products are Biproducts in a Compact Closed Category
math.CT
If a compact closed category has finite products or finite coproducts then it in fact has finite biproducts, and so is semi-additive.
math
694
Exponentiable functors between quantaloid-enriched categories
math.CT
Exponentiable functors between quantaloid-enriched categories are characterized in elementary terms. The proof goes as follows: the elementary conditions on a given functor translate into existence statements for certain adjoints that obey some lax commutativity; this, in turn, is precisely what is needed to prove the ...
math
695
Strict 2-toposes
math.CT
A 2-categorical generalisation of elementary topos is provided and some of the properties of the yoneda structure it generates are explored. Examples relevant to the globular approach to higher category theory are discussed. This paper also contains some expository material on the theory of fibrations internal to a fin...
math
696
Generalized 2-vector spaces and general linear 2-groups
math.CT
In this paper a notion of {\it generalized 2-vector space} is introduced which includes Kapranov and Voevodsky 2-vector spaces. Various kinds of generalized 2-vector spaces are considered and examples are given. The existence of non free generalized 2-vector spaces and of generalized 2-vector spaces which are non Karou...
math
697
Double Clubs
math.CT
We develop a theory of double clubs which extends Kelly's theory of clubs to the pseudo double categories of Pare and Grandis. We then show that the club for symmetric strict monoidal categories on Cat extends to a `double club' on the pseudo double category of `categories, functors, profunctors and transformations'.
math
698
Polycategories via pseudo-distributive laws
math.CT
In this paper, we give a novel abstract description of Szabo's polycategories. We use the theory of double clubs -- a generalisation of Kelly's theory of clubs to `pseudo' (or `weak') double categories -- to construct a pseudo-distributive law of the free symmetric strict monoidal category pseudocomonad on Mod over its...
math
699
2-nerves for bicategories
math.CT
We describe a Cat-valued nerve of bicategories, which associates to every bicategory a simplicial object in Cat, called the 2-nerve. We define a 2-category NHom whose objects are bicategories and whose 1-cells are normal homomorphisms of bicategories, in such a way that the 2-nerve construction becomes a full embedding...
math