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Theorem 9.3. If \( p \) is regular then the second case of Fermat’s Last Theorem has no solutions.
Proof. If \( p \) is regular then \( p \nmid {h}^{ + }\left( {\mathbb{Q}\left( {\zeta }_{p}\right) }\right) \), so Assumption I is satisfied.\n\nFrom formulas in the previous section,\n\n\[ \n{\eta }_{a} = \frac{\omega + {\zeta }^{a}\theta }{1 - {\zeta }^{a}}{\rho }_{a}^{-p} \]\n\n\[ \n= \left( {\omega + {\zeta }^{a}\f...
Yes
Theorem 9.5. Let the notation be as in Proposition 8.18 and Corollary 8.19. If there exists a prime \( l \equiv 1{\;\operatorname{mod}\;p} \) with \( l < {p}^{2} - p \) such that\n\n\[ \n{Q}_{i}^{k} ≢ 1{\;\operatorname{mod}\;l}\;\text{ for all }i \in \left\{ {{i}_{1},\ldots ,{i}_{s}}\right\} ,\n\]\n\nthen the second ca...
Proof. By Corollary \( {8.19}, p \nmid {h}^{ + }\left( {\mathbb{Q}\left( {\zeta }_{p}\right) }\right) \), so Assumption I is satisfied. Suppose that\n\n\[ \n{x}^{p} + {y}^{p} = {z}^{p},\;p \nmid {xy}, p \mid z, z \neq 0,\n\]\n\nwhere \( x, y, z \in \mathbb{Z} \) are relatively prime. Let \( l \) be as in the statement ...
No
Lemma 9.6. \( l \nmid {xy} \).
Proof. Suppose \( l \mid y \), hence \( l \nmid {xz} \). Since\n\n\[ \mathop{\prod }\limits_{{a = 0}}^{{p - 1}}\left( {y - {\zeta }^{a}z}\right) = - {x}^{p} \]\n\nthe standard argument shows that the numbers\n\n\[ y - {\zeta }^{a}z,\;0 \leq a \leq p - 1, \]\n\nare relatively prime in \( \mathbb{Z}\left\lbrack {\zeta }_...
Yes
Lemma 9.7. \( l \mid z \) (this is where \( l < {p}^{2} - p \) is used most strongly).
Proof. Write \( l = 1 + {kp} \) with \( k < p - 1 \) . By the equations obtained in Lemma 9.6 (we only needed \( p \nmid x \) ),\n\n\[ \left( {y - {\zeta }^{a}z}\right) {\sigma }_{a}^{-p} = {\gamma }_{a} = {\gamma }_{-a} = \left( {y - {\zeta }^{-a}z}\right) {\sigma }_{-a}^{-p},\;1 \leq a \leq p - 1. \]\n\nLet \( \widet...
Yes
Lemma 9.9. \( {\eta }_{a}/{\eta }_{b} \) is a pth power.
Proof. Let \( \widetilde{l} \) be a prime of \( \mathbb{Q}\left( {\zeta }_{p}\right) \) lying above \( l \) . Then\n\n\[ \n{\eta }_{a} = \frac{\omega + {\zeta }^{a}\theta }{1 - {\zeta }^{a}}{\rho }_{a}^{-p} = \left( {\omega + {\zeta }^{a}\frac{\omega + \theta }{1 - {\zeta }^{a}}}\right) {\rho }_{a}^{-p}\n\]\n\n\[ \n\eq...
No
Theorem 10.1. Suppose the extension of number fields \( L/K \) contains no unramified abelian subextensions \( F/K \) with \( F \neq K \) . Then \( {h}_{K} \) divides \( {h}_{L} \) . In fact, the norm map from the class group of \( L \) to the class group of \( K \) is surjective.
Proof. The first statement is Proposition 4.11. The second is proved in the appendix on class field theory.
No
Theorem 10.2. Let \( n ≢ 2{\;\operatorname{mod}\;4} \) be arbitrary and let \( {h}_{n} = h\left( {\mathbb{Q}\left( {\zeta }_{n}\right) }\right) \) . If \( 2 \mid {h}_{n}^{ + } \) then \( 2 \mid {h}_{n}^{ - } \) .
Proof. \( \mathbb{Q}\left( {\zeta }_{n}\right) /\mathbb{Q}{\left( {\zeta }_{n}\right) }^{ + } \) is totally ramified at infinity, so Theorem 10.1 implies that the norm map on the ideal class groups\n\n\[ N : C \rightarrow {C}^{ + } \]\n\nis surjective, so \( {h}_{n}^{ - } = {h}_{n}/{h}_{n}^{ + } = \left| {\ker N}\right...
Yes
Theorem 10.3. Let \( K \) be a \( {CM} \) -field. The kernel of the map \( {C}^{ + } \rightarrow C \) from the ideal class group of \( {K}^{ + } \) to that of \( K \) has order 1 or 2 .
Proof. Let \( I \) be an ideal of \( {K}^{ + } \) and suppose \( I = \left( \alpha \right) \) in \( K \) . Then \( \left( 1\right) = \bar{I}/I = \) \( \left( {\bar{\alpha }/\alpha }\right) \), so \( \bar{\alpha }/\alpha \) is a unit, hence a root of unity by Lemma 1.6. This root of unity does not depend on the class of...
Yes
Theorem 10.4. (a) Suppose \( L/K \) is a Galois extension and \( \operatorname{Gal}\left( {L/K}\right) \) is a p-group \( \left( {p = \text{any prime}}\right) \) . Assume there is at most one prime (finite or infinite) which ramifies in \( L/K \) . If \( p \mid {h}_{L} \) then \( p \mid {h}_{K} \) .
Proof. Assume \( p \mid {h}_{L} \) . Let \( H \) be the Hilbert \( p \) -class field of \( L \), so \( H \) is the maximal unramified abelian \( p \) -extension of \( L \) and \( \operatorname{Gal}\left( {H/L}\right) \) is isomorphic to the \( p \) -Sylow subgroup of the ideal class group of \( L \) . Since \( L/K \) i...
Yes
Corollary 10.5. Let \( n \geq 1 \) . Then \( p\left| {h\left( {\mathbb{Q}\left( {\zeta }_{p}\right) }\right) \Leftrightarrow p}\right| h\left( {\mathbb{Q}\left( {\zeta }_{{p}^{n}}\right) }\right) \) .
Proof. Theorems 10.1 and 10.4.
No
Theorem 10.8. Let \( L/K \) be cyclic of degree \( n \) . Let \( p \) be prime, \( p \nmid n \), and assume all fields \( E \) with \( K \subseteq E \subsetneqq L \) satisfy \( p \nmid {h}_{E} \) . Let \( A \) be the p-Sylow subgroup of the ideal class group of \( L \), and let \( f \) be the order of \( p{\;\operatorn...
Proof. Let \( V = {A}^{{p}^{a - 1}}/{A}^{{p}^{a}} \), so \( V \) has \( {p}^{{r}_{a}} \) elements. Let \( \sigma \) generate \( \operatorname{Gal}\left( {L/K}\right) \) . Then \( \sigma \) acts on \( V \) . Let \( v \in V, v \neq 0 \), and suppose the orbit of \( v \) under the action of \( \operatorname{Gal}\left( {L/...
Yes
Theorem 10.11. Let \( p \) be an odd prime. Let \( L \) be a CM-field with \( {\zeta }_{p} \in L \), and let A be the p-Sylow subgroup of the ideal class group of L. Then\n\n\[ \n\text{p-rank}{A}^{ + } \leq 1 + \text{p-rank}{A}^{ - }\text{.} \n\]\n\nLet \( W \) be the roots of unity in \( L \) . If \( L\left( {W}^{1/p}...
Proof. In the notation at the beginning of the section, let \( K = {L}^{ + } \), the maximal real subfield of \( L \) . Then \( G = \operatorname{Gal}\left( {L/K}\right) = \{ 1, J\} \), where \( J = \) complex conjugation, and\n\n\[ \n{A}^{ + } = \frac{1 + J}{2}A,\;{A}^{ - } = \frac{1 - J}{2}A.\n\]\n\nAs in the above t...
Yes
Proposition 10.12. Let \( L \) be a \( {CM} \) -field and let \( {A}_{L} \) and \( {A}_{{L}^{ + }} \) be the 2-Sylow subgroups of the ideal class groups of \( L \) and \( {L}^{ + } \), respectively. Then\n\n\[ \text{2-rank}{A}_{{L}^{ + }} \leq 1 + 2\text{-rank}{A}_{L}^{ - }\text{.} \]
Proof. Let \( i\left( {A}_{{L}^{ + }}\right) \) denote the image in \( {A}_{L} \) and let \( {\left( {A}_{{L}^{ + }}\right) }_{2} \) and \( {\left( {A}_{L}^{ - }\right) }_{2} \) denote the elements of order 2 in the respective groups. As noted above,\n\n\[ i\left( {\left( {A}_{{L}^{ + }}\right) }_{2}\right) \subseteq {...
Yes
Let \( A \) be the p-Sylow subgroup of the ideal class group of \( \mathbb{Q}\left( {\zeta }_{p}\right) \) and let\n\n\[ A = {\bigoplus }_{i = 0}^{p - 2}{\varepsilon }_{i}A \]\n\nbe the decomposition according to idempotents. If \( p \nmid h\left( {\mathbb{Q}{\left( {\zeta }_{p}\right) }^{ + }}\right) \) then\n\n\[ {\v...
Proof. By Theorem 10.14, each \( {\varepsilon }_{i}A \) is a cyclic group. By Proposition 6.16, \( {B}_{1,{\omega }^{-i}} \) annihilates \( {\varepsilon }_{i}A \), so\n\n\[ \left| {{\varepsilon }_{i}A}\right| \leq p\text{-part of}{B}_{1,{\omega }^{-i}}\text{.} \]\n\nSince\n\n\[ \mathop{\prod }\limits_{{i = 3}}^{{p - 2}...
Yes
Corollary 10.17. Suppose \( p \nmid h\left( {\mathbb{Q}{\left( {\zeta }_{p}\right) }^{ + }}\right) \) . Let \( {i}_{1},\ldots ,{i}_{s} \) be the even indices \( i \) such that \( 2 \leq i \leq p - 3 \) and \( p \mid {B}_{i} \) . If\n\n\[ \n{B}_{1,{\omega }^{i - 1}} ≢ 0{\;\operatorname{mod}\;{p}^{2}} \n\] \n\nand \n\n\[...
Proof. Let \( f\left( {T,{\omega }^{i}}\right) = {a}_{0} + {a}_{1}T + \cdots \), with \( {a}_{j} \in {\mathbb{Z}}_{p} \) for all \( p \) . Then, for \( s \in {\mathbb{Z}}_{p} \) , \n\n\[ \n{L}_{p}\left( {s,{\omega }^{i}}\right) = f\left( {{\left( 1 + p\right) }^{s} - 1,{\omega }^{i}}\right) \equiv {a}_{0} + {a}_{1}{sp}...
Yes
Lemma 11.2. Let \( \gamma = {0.577}\ldots \) be the Euler-Mascheroni constant and let \( A \) be a positive integer. Then\n\n\[ \gamma + \log A \leq \mathop{\sum }\limits_{{a = 1}}^{A}\frac{1}{a} \leq \frac{1}{A} + \gamma + \log A. \]
Proof. Since\n\n\[ \log \left( \frac{A + 1}{A}\right) = \frac{1}{A} - \frac{1}{2{A}^{2}} + \frac{1}{3{A}^{3}}\cdots \]\n\nhas alternating signs and decreasing terms, we have\n\n\[ \frac{1}{A} - \frac{1}{2{A}^{2}} < \log \left( \frac{A + 1}{A}\right) < \frac{1}{A}. \]\n\nTherefore\n\n\[ \frac{1}{A + 1} - \log \left( \fr...
Yes
Lemma 11.3. Let \( \pi \left( m\right) \) be the number of distinct prime divisors of \( m \) . Then\n\n\[ \mathop{\sum }\limits_{\substack{{n = 1} \\ {\left( {n, m}\right) = 1} }}^{{jm}}\frac{1}{n} = \left( {\gamma + \log \left( {jm}\right) + \mathop{\sum }\limits_{{p \mid m}}\frac{\log p}{p - 1}}\right) \mathop{\prod...
Proof. We shall use induction on \( \pi \left( m\right) \) . By Lemma 11.2, the lemma is true for \( \pi \left( m\right) = 0 \) . Assume it is true for \( \pi \left( m\right) \) and then replace \( m \) by \( {mq} \), with \( q \) prime, \( \left( {q, m}\right) = 1 \) (the cases \( m{q}^{2} \), etc., are obtained by va...
Yes
Lemma 11.4.\n\n\\[ \n\\mathop{\\sum }\\limits_{{j = 1}}^{N}\\frac{\\log j}{j} < {0.11} + \\frac{1}{2}{\\left( \\log N\\right) }^{2}\\;\\text{ for }N \\geq 1, \n\\]\n\nand\n\n\\[ \n\\mathop{\\sum }\\limits_{{j = 1}}^{N}\\frac{\\log j}{j} < \\frac{1}{2}{\\left( \\log N\\right) }^{2}\\;\\text{ for }N \\geq {21}. \n\\]
Proof. A calculation shows that\n\n\\[ \n\\mathop{\\sum }\\limits_{{j = 1}}^{{21}}\\frac{\\log j}{j} < \\frac{1}{2}{\\left( \\log {21}\\right) }^{2} \n\\]\n\nSince \\( \\left( {\\log x}\\right) /x \\) is decreasing for \\( x > e \\) ,\n\n\\[ \n\\mathop{\\sum }\\limits_{{j = {22}}}^{N}\\frac{\\log j}{j} < {\\int }_{21}^...
Yes
Lemma 11.8 (Polya-Vinogradov). Let \( \chi \neq 1 \) be primitive with conductor \( f \). Let \( S\left( {u,\chi }\right) = \mathop{\sum }\limits_{{0 \leq n < u}}\chi \left( n\right) \). Then \[ \left| {S\left( {u,\chi }\right) }\right| < {f}^{1/2}\log f \]
Proof. Let \( \zeta = {e}^{{2\pi i}/f} \) and let \( \tau \left( \chi \right) = \mathop{\sum }\limits_{{c = 1}}^{{f - 1}}\chi \left( c\right) {\zeta }^{c} \). By Lemma 4.7, \[ \overline{\chi \left( n\right) }\tau \left( \chi \right) = \mathop{\sum }\limits_{c}\chi \left( c\right) {\zeta }^{cn} \] We may assume \( u \) ...
Yes
Lemma 11.9. If \( \chi \) is a primitive nontrivial character of conductor \( f \) and \( 1 \geq \) \( \sigma \geq 1 - 1/{4f} \), then\n\n\[ \left| {{L}^{\prime }\left( {\sigma ,\chi }\right) }\right| \leq \left( {1.3}\right) {\left( \log f\right) }^{2}. \]
Proof. As in the proof of Lemma 11.6, we have for \( \sigma = \operatorname{Re}\left( s\right) > 0 \) ,\n\n\[ L\left( {s,\chi }\right) = \mathop{\sum }\limits_{{n = 1}}^{{f - 1}}\chi \left( n\right) {n}^{-s} + s{\int }_{f}^{\infty }S\left( {u,\chi }\right) {u}^{-s - 1}{du}. \]\n\nDifferentiate:\n\n\[ {L}^{\prime }\left...
Yes
Lemma 11.10. If \( \chi \) is a primitive quadratic character of conductor \( f \), then\n\n\[ L\left( {\sigma ,\chi }\right) \geq 0\;\text{ for }\sigma \geq 1 - \frac{1}{4f}. \]
Proof. By the analytic class number formula (see the discussion following Theorem 4.9),\n\n\[ L\left( {1,\chi }\right) = \left\{ \begin{array}{ll} \frac{{2h}\log \varepsilon }{\sqrt{f}}, & \chi \text{ even,} \\ \frac{2\pi h}{w\sqrt{f}}, & \chi \text{ odd,} \end{array}\right. \]\n\nwhere \( h \) and \( \varepsilon \) ar...
Yes
Lemma 11.11. If \( \chi \) is a quadratic character \( {\;\operatorname{mod}\;m} \), then\n\n\[ L\left( {\sigma ,{\chi }_{m}}\right) \geq 0\;\text{ for }\sigma \geq 1 - 1/{4m} \]
Proof.\n\n\[ L\left( {\sigma ,{\chi }_{m}}\right) = L\left( {\sigma ,\chi }\right) \mathop{\prod }\limits_{{p \mid m}}\left( {1 - \frac{\chi \left( p\right) }{{p}^{\sigma }}}\right) \geq 0 \]\n\nsince \( 1 - 1/{4m} \geq 1 - 1/{4f} \) .
No
Lemma 11.12. If \( \phi \left( m\right) \geq {20} \), then\n\n\[ \mathop{\prod }\limits_{{\chi \neq 1}}L\left( {1,{\chi }_{m}}\right) \geq \frac{1}{{16m\phi }{\left( m\right) }^{1/2}} \]
Proof. We shall use Lemma 11.7 with \( f\left( s\right) = \mathop{\prod }\limits_{{\chi \neq 1}}L\left( {s,{\chi }_{m}}\right) \) and \( \alpha = 1 - 1/{4m} \) . \( M \) is given by Lemma 11.6. Clearly (a) and (c) are satisfied. Since \( f\left( s\right) \zeta \left( s\right) \) is the Dedekind zeta function of \( \mat...
Yes
Lemma 11.13. If \( \phi \left( m\right) \geq {220} \) then\n\n\[ \left| {\mathop{\prod }\limits_{{\chi \text{ odd }}}L\left( {1,{\chi }_{m}}\right) }\right| \geq \frac{1}{{16m\phi }{\left( m\right) }^{1/2}}{\left( {1.7}\right) }^{\left( {2 - \phi \left( m\right) }\right) /4}. \]\n
Proof. Lemmas 11.5 and 11.12.
No
Lemma 11.14.\n\n\[ \mathop{\prod }\limits_{{\chi \text{ odd }}}\mathop{\prod }\limits_{{p \mid m}}{\left( 1 - \frac{\chi \left( p\right) }{p}\right) }^{-1} \geq {e}^{-{7\phi }\left( m\right) /{24}}. \]
Proof. Write \( m = {m}_{p}{m}_{p}^{\prime } \), where \( {m}_{p} \) is a power of \( p \) and \( p \nmid {m}_{p}^{\prime } \) . Then \( \chi \left( p\right) \neq \) \( 0 \Leftrightarrow {f}_{\chi } \mid {m}_{p}^{\prime } \) . There are at most \( \frac{1}{2}\phi \left( {m}_{p}^{\prime }\right) \) such odd characters. ...
Yes
Proposition 11.15. If \( \phi \left( m\right) \geq {220} \) then\n\n\[ \log {h}_{m}^{ - } \geq \frac{1}{4}\log {d}_{m} - \left( {1.37}\right) \phi \left( m\right) \]\n\nwhere \( {d}_{m} \) is the absolute value of the discriminant of \( \mathbb{Q}\left( {\zeta }_{m}\right) \) .
Proof. From the class number formula (in particular, see the discussion preceding Theorem 4.17),\n\n\[ \log {h}_{m}^{ - } = \frac{1}{2}\log \left( \frac{{d}_{m}}{{d}_{m}^{ + }}\right) + \log \mathop{\prod }\limits_{{\chi \text{ odd }}}L\left( {1,{\chi }_{m}}\right) + \log w \]\n\n\[ + \log Q - \frac{\phi \left( m\right...
Yes
Proposition 11.16. Assume \( \phi \left( m\right) \geq {220} \) . If \( m \) is a prime power then\n\n\[ \log {h}_{m}^{ - } \geq \frac{1}{4}\log {d}_{m} - \left( {1.08}\right) \phi \left( m\right) \]\n\nIf \( m \) is arbitrary then\n\n\[ \log {h}_{m}^{ - } \geq \frac{1}{4}\log {d}_{m} - \left( {1.08}\right) \phi \left(...
Proof. In Lemma 11.14, all the factors are 1 if \( m \) is a prime power. If \( m \) is arbitrary, we have, as in the proof of the lemma,\n\n\[ \log \mathop{\prod }\limits_{{\chi \text{ odd }}}\mathop{\prod }\limits_{{p \mid m}}{\left( 1 - \frac{\chi \left( p\right) }{p}\right) }^{-1} \geq - \frac{\phi \left( m\right) ...
Yes
Corollary 11.17. If \( \phi \left( {p}^{a}\right) \geq {220} \), then \( {h}_{{p}^{a}}^{ - } > 1 \) .
Proof. We have\n\n\[ \frac{\log \left( {d}_{{p}^{a}}\right) }{\phi \left( {p}^{a}\right) } = \log \left( {p}^{a}\right) - \frac{\log p}{p - 1} \geq \log \left( {p}^{a}\right) - \log 2 \]\n\n\[ \geq \log \left( {220}\right) - \log \left( 2\right) \geq {4.7}\text{.} \]\n\nTherefore\n\n\[ \log \left( {h}_{{p}^{a}}^{ - }\r...
Yes
Corollary 11.18. \( {h}_{{p}^{a}}^{ - } = 1 \) if and only if \( {p}^{a} \) is one of the following: an odd prime \( p \leq {19} \), or \( 4,8,9,{16},{25},{27},{32} \) (one could also include \( {p}^{a} = 1 \) ).
Proof. We know that \( \phi \left( {p}^{a}\right) < {220} \) . The table in the appendix yields the answer.
No
Lemma 11.22. If \( L/K \) is an extension of degree \( n \) in which no finite primes ramify, then\n\n\[ \n{D}_{L} = {D}_{K}^{n} \n\]\n\nwhere \( {D}_{L} \) and \( {D}_{K} \) are the absolute values of the discriminants of \( L \) and \( K \) , respectively.
Proof. A well-known formula (see Lang [1], pp. 60, 66) states that\n\n\[ \n{D}_{L} = {D}_{K}^{n}N{\mathcal{D}}_{L/K} \n\]\n\nwhere \( N{\mathcal{D}}_{L/K} \) is the norm of the relative different. Since no primes ramify, \( {\mathcal{D}}_{L/K} = \left( 1\right) \) . The result follows.
Yes
Lemma 11.23. Let \( B\left( n\right) \) be the lower bound for \( {D}^{1/n} \) for totally real fields of degree \( \geq n \) (as given in the table of the previous section). Let \( {d}_{m}^{ + } \) and \( {h}_{m}^{ + } \) be the discriminant and class number of \( \mathbb{Q}{\left( {\zeta }_{m}\right) }^{ + } \) . If\...
Proof. Let \( H \) be the Hilbert class field of \( \mathbb{Q}{\left( {\zeta }_{m}\right) }^{ + } \), so \( H/\mathbb{Q}{\left( {\zeta }_{m}\right) }^{ + } \) is an unramified extension of degree \( {h}_{m}^{ + } \), and\n\n\[{n}_{H} = \left\lbrack {H : \mathbb{Q}}\right\rbrack = \frac{1}{2}\phi \left( m\right) {h}_{m}...
Yes
If \( \phi \) is a measure, then\n\n\[ \n{\int }_{X}{fd\phi } : \operatorname{Step}\left( X\right) \rightarrow {\mathbb{C}}_{p}\n\]\n\nextends uniquely to a continuous \( {\mathbb{C}}_{p} \) -linear map\n\n\[ \n{\int }_{X}{fd\phi } : C\left( {X,{\mathbb{C}}_{p}}\right) \rightarrow {\mathbb{C}}_{p}\n\]
Proof. Since the step functions are dense, the map must be unique if it exists.\n\nObserve that if \( K \) is the constant used above and \( {\chi }_{i, a} \) is the characteristic function of the previous section,\n\n\[ \n\left| {{\int }_{X}{\chi }_{i, a}{d\phi }}\right| = \left| {{\phi }_{i}\left( a\right) }\right| \...
Yes
Corollary 12.5. Let \( \phi \) be a measure. Then \( \left( {{\Gamma }_{p}\phi }\right) \left( s\right) \) is an analytic function of \( s \) .
Proof. Let \( \theta = \psi = 1 \) . Clearly any function of the form \( g\left( {{\kappa }_{0}^{s} - 1}\right) \) is analytic.
No
Corollary 12.6. If \( {\int }_{\Delta \times \left( {1 + p{Z}_{p}}\right) }{\theta \psi d\phi } = 0 \) for all \( \theta \in \widehat{\Delta } \) and all \( \psi \) of the second kind, then \( \phi = 0 \) . (In other words, a measure is determined by its values on characters of finite order. Note that \( \theta \left( ...
Proof. Let \( {g}_{\theta } \) be one of the corresponding power series. Then\n\n\[ {g}_{\theta }\left( {\psi \left( {\kappa }_{0}\right) - 1}\right) = 0\;\text{ for all }\psi \]\n\nhence\n\n\[ {g}_{\theta }\left( {{\zeta }_{{p}^{n}} - 1}\right) = 0\;\text{ for all }n. \]\n\nBy the \( p \) -adic Weierstrass Preparation...
Yes
Proposition 12.7. Let \( g \in \mathcal{O}\left\lbrack \left\lbrack T\right\rbrack \right\rbrack \) and let \( d{\widetilde{\phi }}_{a} \) be the corresponding measure on \( \widetilde{X} = {\mathbb{Z}}_{p} \) . For \( k \geq 0 \) , \[ \left( {{D}^{k}g}\right) \left( 0\right) = {\int }_{y \in \widetilde{X}}{y}^{k}d{\wi...
Proof. First let \( g = {\left( 1 + T\right) }^{n} \) . As mentioned above, the left-hand side is \( {n}^{k} \) . The measure \( d\widetilde{\phi } \) is the delta measure \( {\delta }_{n} \), so \[ \int {y}^{k}d\widetilde{\phi } = {n}^{k} \] By linearity, the result holds for polynomials. Let \( g\left( T\right) \in \...
Yes
Proposition 12.8. Let \( g \in \mathcal{O}\left\lbrack \left\lbrack T\right\rbrack \right\rbrack \) and let \( d{\phi }_{g} \) and \( d{\widetilde{\phi }}_{g} \) be the corresponding measures on \( X = 1 + p{\mathbb{Z}}_{p} \) and \( \widetilde{X} = {\mathbb{Z}}_{p} \) . Let \( {\chi }_{{\widetilde{X}}^{ \times }}\left...
Proof. By Proposition 12.7, it suffices to prove the first equality. As usual, let \( N \geq 1 \) be large and write\n\n\[ g\left( T\right) = {P}_{N}\left( T\right) {q}_{N}\left( T\right) + {r}_{N}\left( T\right) \]\n\nThen\n\n\[ {Ug} = U\left( {{P}_{N}{q}_{N}}\right) + U{r}_{N} \]\n\nBut\n\n\[ {P}_{N}\left( {\zeta \le...
Yes
Corollary 12.9. Let \( g \in \mathcal{O}\left\lbrack \left\lbrack T\right\rbrack \right\rbrack \) . Fix a congruence class \( \alpha {\;\operatorname{mod}\;p} - 1 \) . Then there exists \( h\left( T\right) \in \mathcal{O}\left\lbrack \left\lbrack T\right\rbrack \right\rbrack \) such that\n\n\[ \left( {{D}^{k}{Ug}}\righ...
Proof. Decompose\n\n\[ {\widetilde{X}}^{ \times } = {\left( \mathbb{Z}/p\mathbb{Z}\right) }^{ \times } \times \left( {1 + p{\mathbb{Z}}_{p}}\right) \]\n\nThen\n\n\[ \left( {{D}^{k}{Ug}}\right) \left( 0\right) = {\int }_{{\widetilde{X}}^{ \times }}{\omega }^{\alpha }\left( y\right) \langle y{\rangle }^{k}d{\widetilde{\p...
Yes
Proposition 12.11. The universal punctured ordinary distribution \( {A}_{n}^{0} \) on \( \left( {1/n}\right) \mathbb{Z}/\mathbb{Z} \) requires at most \( \phi \left( n\right) + \pi \left( n\right) - 1 \) generators, where \( \pi \left( n\right) \) equals the number of distinct prime factors of \( n \) .
Proof. \( {A}_{n}^{0} \) is generated by\n\n\[ \left\{ {\left. {g\left( \frac{a}{n}\right) }\right| \;\begin{array}{l} a \\ n \end{array} \in \frac{1}{n}\mathbb{Z}/\mathbb{Z},\frac{a}{n} \neq 0}\right\} \]\n\nwith relations\n\n\[ g\left( \frac{a}{r}\right) = \mathop{\sum }\limits_{{k = 0}}^{{\left( {n/r}\right) - 1}}g\...
Yes
Lemma 12.16. Let \( n = m{m}^{\prime } \) with \( {f}_{\chi } \mid m \) and \( \left( {m,{m}^{\prime }}\right) = 1 \) . Then\n\n\[ \mathop{\sum }\limits_{\substack{{a = 1} \\ {\left( {a, n}\right) = 1} }}^{n}\chi \left( a\right) h\left( \frac{a{m}^{\prime }}{n}\right) = \phi \left( {m}^{\prime }\right) \left( {\mathop{...
Proof. See the calculations following the proof of Lemma 8.7.
No
Proposition 12.17. Let \( n = \mathop{\prod }\limits_{{i = 1}}^{s}{p}_{i}^{{e}_{i}} \) . Let I run through all subsets of \( \{ 1,\ldots, s\} \) , except \( \{ 1,\ldots, s\} \), and let \( {n}_{I} = \mathop{\prod }\limits_{{i \in I}}{p}_{i}^{{e}_{i}} \) . Then\n\n\[ \mathop{\sum }\limits_{I}\mathop{\sum }\limits_{\subs...
Proof. See the end of the proof of Theorem 8.3. This is where we need \( \chi \neq 1 \) (if \( \chi = 1 \), include \( I = \{ 1,\ldots, s\} \) and the result holds).
No
Theorem 12.18. Let \( n > 2 \) . For some integers \( a, b, c, d \), we have\n\nUniversal punctured \( = {A}_{n}^{0} \simeq {\mathbb{Z}}^{\phi \left( n\right) + \pi \left( n\right) - 1} \) ,\n\nUniversal even punctured \( = {\left( {A}_{n}^{0}\right) }^{ + } \simeq {\mathbb{Z}}^{\left( {1/2}\right) \phi \left( n\right)...
The proof of Bass' theorem is now immediate. Since\n\n\[ \n{\left( {A}_{n}^{0}\right) }^{ + } \rightarrow \text{group generated by}\left\{ {\log \left| {{\zeta }_{n}^{a} - 1}\right| ,0 < a < n}\right\} \n\]\n\nis surjective, and the latter is free abelian of rank (at least, hence exactly) \( \frac{1}{2}\phi \left( n\ri...
Yes
Proposition 13.1. Let \( {K}_{\infty }/K \) be a \( {\mathbb{Z}}_{p} \) -extension. Then, for each \( n \geq 0 \), there is a unique field \( {K}_{n} \) of degree \( {p}^{n} \) over \( K \), and these \( {K}_{n} \), plus \( {K}_{\infty } \), are the only fields between \( K \) and \( {K}_{\infty } \) .
Proof. The intermediate fields correspond to the closed subgroups of \( {\mathbb{Z}}_{p} \) . Let \( S \neq 0 \) be a closed subgroup and let \( x \in S \) be such that \( {v}_{p}\left( x\right) \) is minimal. Then \( x\mathbb{Z} \), hence \( x{\mathbb{Z}}_{p} \), is in \( S \) . By the choice of \( x \), we must have ...
Yes
Lemma 13.3. Let \( {K}_{\infty }/K \) be a \( {\mathbb{Z}}_{p} \) -extension. At least one prime ramifies in this extension, and there exists \( n \geq 0 \) such that every prime which ramifies in \( {K}_{\infty }/{K}_{n} \) is totally ramified.
Proof. Since the class number of \( K \) is finite, the maximal abelian unramified extension of \( K \) is finite, so some prime must ramify in \( {K}_{\infty }/K \) . We know that only finitely many primes of \( K \) ramify in \( {K}_{\infty }/K \) by Proposition 13.2. Call them \( {h}_{1},\ldots ,{h}_{s} \), and let ...
Yes
Theorem 13.4. Suppose the \( {\mathbb{Z}}_{p} \) -rank of \( {\bar{E}}_{1} \) is \( {r}_{1} + {r}_{2} - 1 - \delta \), with \( \delta \geq 0 \) . Then there are \( {r}_{2} + 1 + \delta \) independent \( {\mathbb{Z}}_{p} \) -extensions of \( K \) . In other words, if \( \widetilde{K} \) is the compositum of all \( {\mat...
Proof. Let \( \widetilde{K} \) be as above and \( F \) the maximal abelian extension of \( K \) which is unramified outside \( p \) . Then \( \widetilde{K} \subseteq F \) . Let \( J \) denote the idèles of \( K \) . By class field theory, there is a closed subgroup \( H \) with \[ {K}^{ \times } \subseteq H \subseteq J...
Yes
Lemma 13.5. \( {U}_{1} \cap H = {U}_{1} \cap \overline{{K}^{ \times }{U}^{\prime \prime }} = \overline{\psi \left( {E}_{1}\right) } \).
Proof. Let \( \varepsilon \in {E}_{1} \). Then \( \psi \left( \varepsilon \right) \in {U}_{1} \). Also\n\n\[ \psi \left( \varepsilon \right) = \left( \varepsilon \right) \left( \frac{\psi \left( \varepsilon \right) }{\varepsilon }\right) \in {K}^{ \times }{U}^{\prime \prime } \]\n\nsince \( \psi \left( \varepsilon \rig...
No
Corollary 13.6. Let \( H \) be the Hilbert class field of \( K \) and let \( F \) be the maximal abelian extension of \( K \) unramified outside \( p \) . Then \[ \operatorname{Gal}\left( {F/H}\right) \simeq \left( {\mathop{\prod }\limits_{{p \mid p}}{U}_{p}}\right) /\bar{E} \] where \( \bar{E} \) is the closure of \( ...
Proof. \( \operatorname{Gal}\left( {F/K}\right) \simeq {J}^{\prime } \), and the closed subgroup \( {J}^{\prime \prime } \) corresponds to \( H \) . Hence \( \operatorname{Gal}\left( {F/H}\right) \simeq {J}^{\prime \prime } \simeq {U}^{\prime }/{U}^{\prime } \cap H \) . The same proof as for Lemma 13.5 shows that \( {U...
No
Lemma 13.7. Suppose \( f, g \in \Lambda \) are relatively prime. Then the ideal \( \left( {f, g}\right) \) is of finite index in \( \Lambda \) .
Proof. Let \( h \in \left( {f, g}\right) \) be of minimal degree. Then \( h = {p}^{s}H \) with \( H = 1 \) or \( H \) distinguished. Suppose \( H \neq 1 \) . Since \( f \) and \( g \) are relatively prime, we may assume \( H \) does not divide \( f \) . But\n\n\[ f = {Hq} + r,\;\deg r < \deg H = \deg h, \]\n\nso\n\n\[ ...
Yes
Lemma 13.8. Suppose \( f, g \in \Lambda \) are relatively prime. Then\n\n(1) the natural map\n\n\[ \Lambda /\left( {fg}\right) \rightarrow \Lambda /\left( f\right) \oplus \Lambda /\left( g\right) \]\n\nis an injection with finite cokernel;\n\n(2) there is an injection\n\n\[ \Lambda /\left( f\right) \oplus \Lambda /\lef...
Proof. (1) Since \( \Lambda \) is a unique factorization domain, the map is an injection. Consider \( \left( {a{\;\operatorname{mod}\;f}, b{\;\operatorname{mod}\;g}}\right) \) . If \( a - b \in \left( {f, g}\right) \), then \( a - b = {fA} + {gB} \), for some \( A, B \) . Let\n\n\[ c = a - {fA} = b + {gB}. \]\n\nThen\n...
Yes
Proposition 13.9. The prime ideals of \( \Lambda \) are \( 0,\left( {p, T}\right) ,\left( p\right) \), and the ideals \( \left( {P\left( T\right) }\right) \) where \( P\left( T\right) \) is irreducible and distinguished. The ideal \( \left( {p, T}\right) \) is the unique maximal ideal.
Proof. All the above are easily seen to be prime ideals. Let \( h \neq 0 \) be prime. Let \( h \in p \) be of minimal degree. Then \( h = {p}^{s}H \) with \( H = 1 \) or \( H \) distinguished. Since \( p \) is prime, \( p \in p \) or \( H \in p \) . If \( 1 \neq H \in p \) then \( H \) must be irreducible by the minima...
Yes
Lemma 13.10. Let \( f \in \Lambda \) with \( f \notin {\Lambda }^{ \times } \) . Then \( \Lambda /\left( f\right) \) is infinite.
Proof. We may assume \( f \neq 0 \) . It suffices to consider \( f = p \) and \( f = \) distinguished. If \( f = p,\Lambda /\left( f\right) \simeq \mathbb{Z}/p\mathbb{Z}\left\lbrack \left\lbrack T\right\rbrack \right\rbrack \) . If \( f \) is distinguished, use the division algorithm.
No
Lemma 13.11. \( \Lambda \) is a Noetherian ring.
Proof. It is known (Lang’s Algebra) that if \( A \) is Noetherian then so is \( A\left\lbrack \left\lbrack T\right\rbrack \right\rbrack \) . One could also use the Hilbert basis theorem \( (A \) Noetherian \( \Rightarrow A\left\lbrack T\right\rbrack \) Noetherian) since the generators of an ideal may always be assumed ...
No
Lemma 13.16 (Nakayama’s Lemma). Let \( X \) be a compact \( \Lambda \) -module. Then\n\n\[ X\text{is finitely generated over}\Lambda \Leftrightarrow X/\left( {p, T}\right) X\text{is finite.} \]\n\nIf \( {x}_{1},\ldots ,{x}_{n} \) generate \( X/\left( {p, T}\right) X \) over \( \mathbb{Z} \), then they also generate \( ...
Proof. Consider a small neighborhood \( U \) of 0 in \( X \) . Since \( {\left( p, T\right) }^{n} \rightarrow 0 \) in \( \Lambda \) , each \( z \in X \) has a neighborhood \( {U}_{z} \) such that \( {\left( p, T\right) }^{n}{U}_{z} \subseteq U \) for large \( n \) . Since \( X \) is compact, finitely many \( {U}_{z} \)...
Yes
Lemma 13.20. Assume \( E \) is as in Proposition 13.19, with \( r = 0 \) . Then\n\n\[ m = 0 \Leftrightarrow p - \operatorname{rank}\left( {E/{v}_{n, e}E}\right) \text{is bounded as} n \rightarrow \infty \text{.} \]
Proof. Recall that the \( p \) -rank of a finite abelian group \( A \) is the number of direct summands of \( p \) -power order when \( A \) is decomposed into cyclic groups of prime power order. It is also equal to\n\n\[ {\dim }_{\mathbb{Z}/p\mathbb{Z}}\left( {A/{pA}}\right) \]\n\nRecall that \( {v}_{n, e} \) is disti...
Yes
Proposition 13.22. Suppose \( {K}_{\infty }/K \) is a \( {\mathbb{Z}}_{p} \) -extension in which exactly one prime is ramified, and assume it is totally ramified. Then\n\n\[ \n{A}_{n} \simeq {X}_{n} \simeq X/\left( {{\left( 1 + T\right) }^{{p}^{n}} - 1}\right) X \]\n\nand\n\n\[ \np \nmid {h}_{0} \Leftrightarrow p \nmid...
Proof. Since \( {K}_{\infty }/K \) satisfies the \
No
Proposition 13.23. \( \mu = 0 \Leftrightarrow p - \operatorname{rank}\left( {A}_{n}\right) \) is bounded as \( n \rightarrow \infty \) .
Proof. We have \( {Y}_{e} \sim E \) with \( E \) as in Lemma 13.20. By the lemma, \( \mu = 0 \Leftrightarrow \) \( p \) -rank \( \left( {E/{v}_{n, e}E}\right) \) is bounded. From the proof of Lemma 13.21, we have an exact sequence\n\n\[ 0 \rightarrow {C}_{n} \rightarrow {Y}_{e}/{v}_{n, e}Y \rightarrow E/{v}_{n, e}E \ri...
Yes
Proposition 13.24. Let \( p \) be prime. Suppose \( K \) is a CM-field with \( {\zeta }_{p} \in K \) and let \( {K}_{\infty }/K \) be the cyclotomic \( {\mathbb{Z}}_{p} \) -extension. Then\n\n\[ \mu = 0 \Leftrightarrow {\mu }^{ - } = 0. \]
Proof. \
No
Proposition 13.25. Suppose \( {K}_{\infty }/K \) is a \( {\mathbb{Z}}_{p} \) -extension and assume \( \mu = 0 \) . Then\n\n\[ \nX \simeq \mathop{\lim }\limits_{ \leftarrow }{A}_{n} \simeq {\mathbb{Z}}_{p}^{\lambda } \oplus \left( {\text{ finite }p\text{-group }}\right)\n\]\n\nas \( {\mathbb{Z}}_{p} \) -modules.
Proof. We have\n\n\[ \nX \sim E = {\bigoplus }_{j}\Lambda /\left( {{g}_{j}\left( T\right) }\right)\n\]\n\nwhere each \( {g}_{j} \) is distinguished and \( \sum \deg {g}_{j} = \lambda \) . By the division algorithm,\n\n\[ \n\Lambda /\left( {{g}_{j}\left( T\right) }\right) \simeq {\mathbb{Z}}_{p}^{\deg {g}_{j}}\n\]\n\nTh...
Yes
Proposition 13.26. Let \( p \) be odd. Suppose \( K \) is a CM-field and \( {K}_{\infty }/K \) is the cyclotomic \( {\mathbb{Z}}_{p} \) -extension of \( K \) . Then the map\n\n\[ \n{A}_{n}^{ - } \rightarrow {A}_{n + 1}^{ - }\n\]\n\nis injective.
Proof. Suppose \( I \) is an ideal in \( {A}_{n} \) which becomes principal in \( {K}_{n + 1} \), so\n\n\[ \nI = \left( \alpha \right) \;\text{ with }\alpha \in {K}_{n + 1}.\n\]\n\nLet \( \sigma \) be a generator for \( \operatorname{Gal}\left( {{K}_{n + 1}/{K}_{n}}\right) \) . Then\n\n\[ \n\left( {\alpha }^{\sigma - 1...
Yes
Lemma 13.27. If \( {\varepsilon }_{1} \in {W}_{n + 1} \) and \( N{\varepsilon }_{1} = 1 \) then \( {\varepsilon }_{1} = {\varepsilon }_{2}^{\sigma - 1} \) with \( {\varepsilon }_{2} \in {W}_{n + 1} \) (so \( {H}^{1}\left( {\operatorname{Gal}\left( {{K}_{n + 1}/{K}_{n}}\right) ,{W}_{n + 1}}\right) = 0). \)
Proof. Hilbert’s Theorem 90 tells us that \( {\varepsilon }_{1} = {y}^{\sigma - 1} \) with \( y \in {K}_{n + 1} \), but we already know this with \( y = {\alpha }_{1} \) . We want \( y \in {W}_{n + 1} \) . Consider the following two sequences:\n\n\[ 1 \rightarrow {W}_{n} \rightarrow {W}_{n + 1}\xrightarrow[]{\sigma - 1...
Yes
Proposition 13.28. Let \( p \) be odd, let \( K \) be a \( {CM} \) -field, and let \( {K}_{\infty }/K \) be the cyclotomic \( {\mathbb{Z}}_{p} \) -extension. Then \( {X}^{ - } = \mathop{\lim }\limits_{ \leftarrow }{A}_{n}^{ - } \) contains no finite \( \Lambda \) -submodules. Therefore there is an injection, with finit...
Proof. Suppose \( F \subseteq {X}^{ - } \) is a finite \( \Lambda \) -module. Let \( {\gamma }_{0} \) be a generator of \( \operatorname{Gal}\left( {{K}_{\infty }/K}\right) \) . Since \( F \) is finite, \( {\gamma }_{0}^{{p}^{n}} \) acts trivially on \( F \) for all sufficiently large \( n \) , say \( n \geq {n}_{0} \)...
Yes
Let \( p \) be odd. Let \( K \) be a CM-field and let \( {K}_{\infty }/K \) be the cyclotomic \( {\mathbb{Z}}_{p} \) -extension. If \( {\mu }^{ - } = 0 \) then\n\n\[ \n{X}^{ - } \simeq {\mathbb{Z}}_{p}^{{\lambda }^{ - }}\n\]
Proof. Proposition 13.28 plus the analogue of Proposition 13.25 for \( {X}^{ - } \) .
No
Theorem 13.31. \( {\mathcal{X}}_{\infty } \sim {\Lambda }^{{r}_{2}} \oplus \) ( \( \Lambda \) -torsion).
One advantage of using \( {\mathcal{X}}_{\infty } \) rather than \( X \) is that it is easier to describe how \( {M}_{\infty } \) is generated. Since all \( p \) -power roots of unity are in \( {K}_{\infty },{M}_{\infty }/{K}_{\infty } \) is a Kummer extension. There is a subgroup\n\n\[ \nV \subseteq {K}_{\infty }^{ \t...
Yes
Proposition 13.32. \( {\varepsilon }_{j}{\mathcal{X}}_{\infty }\left( {-1}\right) \simeq {\operatorname{Hom}}_{{\mathbb{Z}}_{p}}\left( {{\varepsilon }_{i}{A}_{\infty },{\mathbb{Q}}_{p}/{\mathbb{Z}}_{p}}\right) \) as \( \Lambda \) -modules, where \( i + j \equiv 1{\;\operatorname{mod}\;\left| \Delta \right| } \) and \( ...
Proof. We shall show more generally that\n\n\[ \n{\operatorname{Hom}}_{{\mathbb{Z}}_{p}}\left( {B,{\mathbb{Q}}_{p}/{\mathbb{Z}}_{p}}\right) \simeq {\operatorname{Hom}}_{{\mathbb{Z}}_{p}}\left( {B,{W}_{{p}^{\infty }}}\right) { \otimes }_{{\mathbb{Z}}_{p}}{T}^{\left( -1\right) }\n\] \n\nfor any \( \Lambda \) -module \( B...
Yes
Lemma 13.33. Let \( u \in {U}_{1} \) and let \( 1 \leq n \leq p - 2 \) . Then \( {\phi }_{k}\left( u\right) = 0 \) for \( 1 \leq k \leq \) \( n \Leftrightarrow u \equiv 1{\;\operatorname{mod}\;{\left( {\zeta }_{p} - 1\right) }^{n + 1}}. \)
Proof. If \( u \equiv 1{\;\operatorname{mod}\;{\left( {\zeta }_{p} - 1\right) }^{n + 1}} \) we may take \( f\left( T\right) = 1 + {T}^{n + 1}g\left( T\right) \) with \( g \in \Lambda \) . Since \( {f}^{\prime }\left( T\right) \in {T}^{n}\Lambda ,{\phi }_{k}\left( u\right) = 0 \) for all \( k \leq n \) .\n\nConversely, ...
Yes
Lemma 13.34. Let \( {\sigma }_{a} \in \operatorname{Gal}\left( {\mathbb{Q}\left( {\zeta }_{p}\right) /\mathbb{Q}}\right) \) . Then\n\n\[{\phi }_{k}\left( {{\sigma }_{a}u}\right) = {a}^{k}{\phi }_{k}\left( u\right)\]
Proof. Let \( u = f\left( {{\zeta }_{p} - 1}\right) \) . Define\n\n\[g\left( T\right) = f\left( {{\left( 1 + T\right) }^{a} - 1}\right) .\]\n\nThen \( {\sigma }_{a}u = g\left( {{\zeta }_{p} - 1}\right) \), and\n\n\[\left( {1 + T}\right) \frac{{g}^{\prime }}{g} = a{\left( 1 + T\right) }^{a}\frac{{f}^{\prime }}{f}\left( ...
Yes
Lemma 13.35. Let \( {\varepsilon }_{i},0 \leq i \leq p - 2 \), be the idempotents of \( {\mathbb{Z}}_{p}\left\lbrack {\operatorname{Gal}\left( {\mathbb{Q}\left( {\zeta }_{p}\right) /\mathbb{Q}}\right. }\right\rbrack \) .\n\nIf \( u \in {U}_{1} \) then\n\n\[ \n{\phi }_{k}\left( {{\varepsilon }_{i}u}\right) = \left\{ \be...
Proof. By Lemma 13.34,\n\n\[ \n{\phi }_{k}\left( {{\varepsilon }_{i}u}\right) = \frac{1}{p - 1}\mathop{\sum }\limits_{{a = 1}}^{{p - 1}}{\omega }^{-i}\left( a\right) {a}^{k}{\phi }_{k}\left( u\right) \equiv \left\{ \begin{array}{ll} 0{\;\operatorname{mod}\;p}, & \text{ if }k \neq i, \\ {\phi }_{k}\left( u\right) {\;\op...
Yes
If \( i ≢ 1{\;\operatorname{mod}\;p} - 1 \) then \( {\varepsilon }_{i}{U}_{1} \) is cyclic as a \( {\mathbb{Z}}_{p} \) -module. For \( i = 1 \) , \( {\varepsilon }_{1}{U}_{1} \simeq \left\langle {\zeta }_{p}\right\rangle \times \) (cyclic \( {\mathbb{Z}}_{p} \) -module). If \( 2 \leq i \leq p - 2 \) and \( u \in {\vare...
Proof. First, let \( i \geq 1 \) be arbitrary. Since \( \left( {{\zeta }_{p}^{a} - 1}\right) /\left( {{\zeta }_{p} - 1}\right) \equiv a{\;\operatorname{mod}\;\left( {{\zeta }_{p} - 1}\right) } \), \[ {\eta }_{i}\overset{\text{ def }}{ = }{\left( 1 - {\left( {\zeta }_{p} - 1\right) }^{i}\right) }^{{\varepsilon }_{i}} = ...
Yes
Corollary 13.37. Let \( 2 \leq i \leq p - 2 \) . There exists \( \lambda = {\lambda }_{i} \neq 1 \) with \( {\lambda }^{p - 1} = 1 \) such that\n\n\[{\xi }_{i} = {\varepsilon }_{i}\left( \frac{\lambda - {\zeta }_{p}}{\omega \left( {\lambda - 1}\right) }\right)\]\n\ngenerates \( {\varepsilon }_{i}{U}_{1} \) . (We divide...
Proof. By Lemma 13.36, it suffices to find \( \lambda \) such that \( {\phi }_{i}\left( {\xi }_{i}\right) \neq 0 \), and by Lemma 13.35, we can work with \( \left( {\lambda - {\zeta }_{p}}\right) /\omega \left( {\lambda - 1}\right) \) . Let\n\n\[f\left( T\right) = \frac{\lambda - 1 - T}{\omega \left( {\lambda - 1}\righ...
Yes
Theorem 13.38. Let \( u = \left( {u}_{n}\right) \in U \) . Then there exists a unique \( {f}_{u} \in \Lambda \) such that\n\n\[ \n{f}_{u}\left( {{\zeta }_{{p}^{n + 1}} - 1}\right) = {u}_{n}\;\text{ for all }n \geq 0.\n\]\n\nThe map\n\n\[ \nU \rightarrow {\Lambda }^{ \times }\n\]\n\n\[ \nu \mapsto {f}_{u}\n\]\n\ngives a...
Proof. Corollary 7.4 implies the uniqueness of \( {f}_{u} \) .\n\nFor simplicity, let \( {v}_{n} = {\zeta }_{{p}^{n + 1}} - 1 \) . Assume for the moment that \( {f}_{u} \) exists. Since\n\n\[ \n{f}_{u}\left( 0\right) \equiv {f}_{u}\left( {{\zeta }_{p} - 1}\right) = {u}_{0} \equiv 1{\;\operatorname{mod}\;\left( {{\zeta ...
Yes
There exists a unique map \( N : \Lambda \rightarrow \Lambda \) such that \[ \left( {Nf}\right) \left( {{\left( 1 + T\right) }^{p} - 1}\right) = \mathop{\prod }\limits_{{{\zeta }^{p} = 1}}f\left( {\zeta \left( {1 + T}\right) - 1}\right) . \]
Proof. Let \( g\left( T\right) \) be the power series on the right, defined by the product. Observe that for \( {\zeta }^{p} = 1 \) , \[ g\left( {\zeta \left( {1 + T}\right) - 1}\right) = g\left( T\right) . \] Suppose we have \( {a}_{0},\ldots ,{a}_{n - 1} \in {\mathbb{Z}}_{p} \) and \( {g}_{n}\left( T\right) \in \Lamb...
Yes
Lemma 13.40. Let \( f \in \Lambda \) . Then\n\n\[ \left( {Nf}\right) \left( {v}_{n - 1}\right) = {N}_{n, n - 1}\left( {f\left( {v}_{n}\right) }\right) \]
Proof. \( \left( {Nf}\right) \left( {v}_{n - 1}\right) = \left( {Nf}\right) \left( {{\left( 1 + {v}_{n}\right) }^{p} - 1}\right) \)\n\n\[ = \prod f\left( {\zeta \left( {1 + {v}_{n}}\right) - 1}\right) = {N}_{n, n - 1}\left( {f\left( {v}_{n}\right) }\right) \] \n\nas in a previous calculation.
Yes
Lemma 13.41. Let \( f \in \Lambda \) and assume \( f\left( {{\left( 1 + T\right) }^{p} - 1}\right) \equiv 1{\;\operatorname{mod}\;{p}^{k}}\Lambda \) . Then \( f\left( T\right) \equiv 1{\;\operatorname{mod}\;{p}^{k}}\Lambda \)
Proof. We may assume \( f \neq 1 \) . Let\n\n\[ f\left( T\right) = 1 + {p}^{\mu }\mathop{\sum }\limits_{{i = 0}}^{\infty }{a}_{i}{T}^{i} \]\n\nfor some \( \mu \geq 0 \), with \( \mu \) maximal. Let \( {a}_{n} \) be the first coefficient such that \( p \nmid {a}_{n} \) . Then\n\n\[ \mathop{\sum }\limits_{{i = 0}}^{\inft...
Yes
Corollary 13.42. \( N : {\Lambda }^{ \times } \rightarrow {\Lambda }^{ \times } \) is continuous.
Proof. Since \( N \) is a homomorphism it suffices to check continuity at 1 . Lemma 13.41 and the definition of \( N \) yield the result.
No
Lemma 13.43. Suppose \( f \in {\Lambda }^{ \times } \) . Then\n\n\[ \frac{{N}^{k}f}{f} \equiv 1{\;\operatorname{mod}\;p}\Lambda \]\n\nfor all \( k \geq 0 \) .
Proof. Since\n\n\[ \frac{{N}^{k}f}{f} = \frac{N\left( {{N}^{k - 1}f}\right) }{{N}^{k - 1}f}\cdots \frac{N\left( f\right) }{f} \]\n\nit suffices to consider \( k = 1 \) . We have\n\n\[ \frac{\left( {Nf}\right) \left( {{\left( 1 + T\right) }^{p} - 1}\right) }{f\left( {{\left( 1 + T\right) }^{p} - 1}\right) } = \frac{\pro...
Yes
Lemma 13.44. Let \( k \geq 1 \) . Then\n\n\[ f \equiv 1{\;\operatorname{mod}\;{p}^{k}}\Lambda \Rightarrow {Nf} \equiv 1{\;\operatorname{mod}\;{p}^{k + 1}}\Lambda . \]\n
Proof. Write \( f\left( T\right) = 1 + {p}^{k}{f}_{1}\left( T\right) \) . Then\n\n\[ f\left( {\zeta \left( {1 + T}\right) - 1}\right) \equiv 1 + {p}^{k}{f}_{1}\left( T\right) {\;\operatorname{mod}\;\left( {{\zeta }_{p} - 1}\right) }{p}^{k}. \]\n\nTherefore\n\n\[ \left( {Nf}\right) \left( {{\left( 1 + T\right) }^{p} - 1...
Yes
Corollary 13.45. Let \( m \geq k \geq 0 \) and let \( f \in {\Lambda }^{ \times } \) . Then\n\n\[ {N}^{m}f \equiv {N}^{k}f{\;\operatorname{mod}\;{p}^{k + 1}}.\]
Proof. Lemma 13.43 implies \( {N}^{m - k}f/f \equiv 1{\;\operatorname{mod}\;p}\Lambda \) . Lemma 13.44 yields the result.
No
Corollary 13.46. Let \( f \in {\Lambda }^{ \times } \) . Then \( {N}^{\infty }f = \lim {N}^{k}f \) exists.
Proof. Corollary 13.45, plus the completeness of \( \Lambda \) .
No
Lemma 13.48. Let \( u \in U \) be associated to \( {f}_{u} \), and let\n\n\[ x = \sum {b}_{a}{\sigma }_{a} \in {\mathbb{Z}}_{p}\left\lbrack {\operatorname{Gal}\left( {\mathbb{Q}\left( {\zeta }_{{p}^{\infty }}\right) /\mathbb{Q}}\right) }\right\rbrack \]\n\nThen\n\n\[ {f}_{{u}^{x}}\left( T\right) = \prod {f}_{u}{\left( ...
It is trivial to check that everything above is defined; for example,\n\n\[ {\left( 1 + T\right) }^{a} = \sum \left( \begin{array}{l} a \\ n \end{array}\right) {T}^{n} \in \Lambda \]
No
Lemma 13.49. Let \( a \in {\mathbb{Z}}_{p}^{ \times } \) and \( {\sigma }_{a} \in \operatorname{Gal}\left( {\mathbb{Q}\left( {\zeta }_{{p}^{\infty }}\right) /\mathbb{Q}}\right) \) . Then, for \( k \geq 1 \) , \[ {\delta }_{k}\left( {{\sigma }_{a}u}\right) = {a}^{k}{\delta }_{k}\left( u\right) \]
Proof. See the proof of Lemma 13.34.
No
Lemma 13.50. If \( u \in U \) then\n\n\[{\delta }_{k}\left( {{\varepsilon }_{i}u}\right) = \left\{ \begin{array}{ll} 0, & \text{ if }k ≢ i{\;\operatorname{mod}\;p} - 1 \\ {\delta }_{k}\left( u\right) , & \text{ if }k \equiv i{\;\operatorname{mod}\;p} - 1. \end{array}\right.\]
Proof. See the proof of Lemma 13.35. Note that\n\n\[{\varepsilon }_{i} = \frac{1}{p - 1}\mathop{\sum }\limits_{{a = 1}}^{{p - 1}}{\omega }^{-i}\left( a\right) {\sigma }_{\omega \left( a\right) }\]\n\nis the idempotent since \( \operatorname{Gal}\left( {\mathbb{Q}\left( {\zeta }_{p}\right) /\mathbb{Q}}\right) \) corresp...
No
Proposition 13.51. Let \( 2 \leq i \leq p - 1 \) . There exists \( {h}_{i}\left( T\right) \in {\Lambda }^{ \times } \) such that \n\n\[ \n\left( {1 - {p}^{k - 1}}\right) {\delta }_{k}\left( {\xi }_{i}^{\infty }\right) = {h}_{i}\left( {{\kappa }_{0}^{k} - 1}\right) \;\text{ for }k \equiv i{\;\operatorname{mod}\;p} - 1. ...
Proof. By Lemma 13.50 we may compute \n\n\[ \n{\delta }_{k}\left( \frac{\lambda - {\zeta }_{{p}^{n + 1}}}{\omega \left( {\lambda - 1}\right) }\right) \n\] \n\nLet \n\n\[ \nf\left( T\right) = \left( {1 + T}\right) \frac{d}{dT}\log \left( \frac{\lambda - \left( {1 + T}\right) }{\omega \left( {\lambda - 1}\right) }\right)...
Yes
Let \( h\left( T\right) \in \Lambda \) and \( u \in U \) . Then\n\n\[ {\delta }_{k}\left( {h\left( T\right) u}\right) = h\left( {{\kappa }_{0}^{k} - 1}\right) {\delta }_{k}\left( u\right) \]
Proof. Since both sides are continuous in \( h \), we may assume \( h \) is a polynomial; by linearity, we may assume \( h\left( T\right) = {\left( 1 + T\right) }^{n} \) . Then \( h\left( T\right) u = {\gamma }_{0}^{n}u \) . By Lemma 13.49,\n\n\[ {\delta }_{k}\left( {{\gamma }_{0}^{n}u}\right) = {\kappa }_{0}^{nk}{\del...
Yes
Lemma 13.53. Let \( {u}_{n} \in {U}_{1}^{\left( n\right) } \). Then\n\n\[ \n{u}_{n} \in {U}_{n}^{\prime } \Leftrightarrow \text{ for all }m \geq n\text{, there exists }{u}_{m} \in {U}_{1}^{\left( m\right) }\text{ with }{N}_{m, n}\left( {u}_{m}\right) = {u}_{n}\text{. }\n\]
Proof. For simplicity, let \( {K}_{m} = {\mathbb{Q}}_{p}\left( {\zeta }_{{p}^{m + 1}}\right) \). An element \( a \in 1 + p{\mathbb{Z}}_{p} \) yields \( {\sigma }_{a} \in \operatorname{Gal}\left( {{K}_{m}/{\mathbb{Q}}_{p}}\right) \), and\n\n\[ \n{\sigma }_{a} = 1 \Leftrightarrow a \equiv 1{\;\operatorname{mod}\;{p}^{m +...
Yes
Theorem 14.2. If \( K/{\mathbb{Q}}_{p} \) is a finite abelian extension, then\n\n\[ K \subseteq {\mathbb{Q}}_{p}\left( {\zeta }_{n}\right) \]\n\nfor some \( n \) .
Proof. We first show it suffices to prove 14.2.\n\n## 14.2 (for all \( p \) ) \( \Rightarrow \) 14.1 .\n\nAssume \( K/\mathbb{Q} \) is abelian. Let \( p \) be a prime which ramifies in this extension. Let \( {K}_{p} \) be the completion at a prime above \( p \) . Then \( {K}_{p}/{\mathbb{Q}}_{p} \) is abelian, so\n\n\[...
No
Lemma 14.3. If \( F/\mathbb{Q} \) is an extension in which no finite prime ramifies, then \( F = \mathbb{Q} \) .
Proof. A theorem of Minkowski (see Exercise 2.5) states that every ideal class of \( F \) contains an integral ideal of norm less than or equal to\n\n\[ \frac{n!}{{n}^{n}}{\left( \frac{4}{\pi }\right) }^{{r}_{2}}\sqrt{{d}_{F}} \]\n\nwhere \( n = \left\lbrack {F : \mathbb{Q}}\right\rbrack ,{d}_{F} \) is the absolute val...
Yes
Lemma 14.4. Let \( K \) and \( L \) be finite extensions of \( {\mathbb{Q}}_{p} \) such that \( K/L \) is unramified. Then\n\n(a) \( K = L\left( {\zeta }_{n}\right) \) for some \( n \) with \( p \nmid n \), and\n\n(b) \( \operatorname{Gal}\left( {K/L}\right) \) is cyclic.\n\nAlso, for fixed \( L \) and for every intege...
We sketch the proof. First consider (a) and (b), and assume \( K/L \) is Galois. Let \( {\mathcal{O}}_{K} \) and \( {h}_{K} \) be the integers and maximal ideal for \( K \) and define \( {\mathcal{O}}_{L} \) and \( {h}_{L} \) similarly. Since \( K/L \) is unramified, there is a canonical isomorphism\n\n\[ \operatorname...
Yes
Lemma 14.5. Let \( K \) and \( L \) be finite extensions of \( {\mathbb{Q}}_{p} \) and let \( {h}_{L} \) be the maximal ideal of the integers of \( L \) . Suppose \( K/L \) is totally ramified of degree \( e \) with \( p \nmid e \) (i.e., \( K/L \) is tamely ramified). Then there exists \( \pi \in L \) of order 1 at \(...
Proof. Let \( \left| x\right| \) be the absolute value on \( {\mathbb{C}}_{p} \) ( \( = \) completion of the algebraic closure of \( {\mathbb{Q}}_{p} \) ). Let \( {\pi }_{0} \in {\mathcal{M}}_{L} \) be of order 1 . Choose \( \beta \in K \) to be a uniformizing parameter, so that \[ {\left| \beta \right| }^{e} = \left| ...
Yes
Lemma 14.6. \( {\mathbb{Q}}_{p}\left( {\left( -p\right) }^{1/\left( {p - 1}\right) }\right) = {\mathbb{Q}}_{p}\left( {\zeta }_{p}\right) \).
Proof. Let\n\n\[ g\left( X\right) = \frac{{\left( X + 1\right) }^{p} - 1}{X} \]\n\n\[ = {X}^{p - 1} + p{X}^{p - 2} + \cdots + p. \]\n\nThen\n\n\[ 0 = g\left( {{\zeta }_{p} - 1}\right) \equiv {\left( {\zeta }_{p} - 1\right) }^{p - 1} + p{\;\operatorname{mod}\;{\left( {\zeta }_{p} - 1\right) }^{p}}, \]\n\nso\n\n\[ u = \f...
Yes
Lemma 14.7. Let \( F \) be a field of characteristic \( \neq p \), let \( M = F\left( {\zeta }_{p}\right) \), and let \( L = M\left( {a}^{1/p}\right) \) for some \( a \in M \) . Define the character \( \omega : \operatorname{Gal}\left( {M/F}\right) \rightarrow {\mathbb{Z}}_{p}^{ \times } \) by \( \sigma {\zeta }_{p} = ...
Proof of Lemma 14.7. Let \( G = \operatorname{Gal}\left( {M/F}\right) \) and \( H = \operatorname{Gal}\left( {L/M}\right) \) . Then \( G \) acts on \( H \) as follows. If \( \sigma \in G \), extend it to an element of \( \operatorname{Gal}\left( {L/F}\right) \) . Then define \( {h}^{\sigma } = {\sigma h}{\sigma }^{-1} ...
Yes
Lemma 14.9. \( {A}^{2} + {B}^{2} = - 1 \) has no solutions in \( {\mathbb{Q}}_{2} \) .
Proof. We may transform this to\n\n\[ \n{A}_{1}^{2} + {A}_{2}^{2} + {A}_{3}^{2} = 0 \n\] \n\nwith \( {A}_{i} \in {\mathbb{Z}}_{2},1 \leq i \leq 3 \), and \( 2 \nmid {A}_{i} \) for some \( i \) . But there are no nontrivial solutions mod 8 . This completes the proof of the lemma.
Yes
Theorem 15.2. Let \( F \) be a totally real abelian number field with \( \Delta = \operatorname{Gal}\left( {F/\mathbb{Q}}\right) \) , let \( E \) be the group of units of the ring of integers of \( F \), let \( {C}^{\prime } \) be the group of cyclotomic units defined above, and let \( A \) be the class group of \( F \...
Proof. Choose \( n \) large enough that \( {p}^{n} > \left| A\right| \) and \( {p}^{n} > \left| {E/{C}^{\prime }}\right| \) . Then the Sylow \( p \) -subgroup of \( A \) is isomorphic to \( A/{A}^{{p}^{n}} \) and the Sylow \( p \) -subgroup of \( E/{C}^{\prime } \) is isomorphic to \( E/{E}^{{p}^{n}}{C}^{\prime } \) . ...
Yes
Lemma 15.3. Let \( \delta \in {C}^{\prime } \) . There exists a unit \( \varepsilon \in L \) such that \( {N}_{L/F}\left( \varepsilon \right) = 1 \) and \( \varepsilon \equiv \delta \left( {{\;\operatorname{mod}\;\sigma }\mathcal{L}}\right) \) for all \( \sigma \) .
Proof. From the definition of \( {C}^{\prime } \), we can write \( \delta = \pm {N}_{\mathbf{Q}\left( {\zeta }_{m}\right) /F}\left( {\mathop{\prod }\limits_{a}{\left( {\zeta }_{m}^{a} - 1\right) }^{{b}_{a}}}\right) \) . Let \( \ell ,\lambda ,\mathcal{L} \), and \( \sigma \) be as above. Note that \( \ell \nmid m \) sin...
Yes
Lemma 15.5. \( {\bar{\varepsilon }}_{\rho }{\mathbb{F}}_{p}\left\lbrack \Delta \right\rbrack \) is an irreducible \( {\mathbb{F}}_{p}\left\lbrack \Delta \right\rbrack \) -module.
Proof. Suppose \( 0 \neq N \subsetneqq {\bar{\varepsilon }}_{\rho }{\mathbb{F}}_{p}\left\lbrack \Delta \right\rbrack \) . Then \( 0 \neq N \otimes {\overline{\mathbb{F}}}_{p} \subsetneqq {\bar{\varepsilon }}_{\rho }{\overline{\mathbb{F}}}_{p}\left\lbrack \Delta \right\rbrack \) (the inequalities hold because the dimens...
Yes
Lemma 15.6. Suppose \( \theta \in {\varepsilon }_{\rho }\mathbb{Z}/{p}^{n}\mathbb{Z}\left\lbrack \Delta \right\rbrack \) and \( {p}^{a} \) is the highest power of \( p \) dividing \( \theta \), with \( 0 \leq a < n \) . Then there exists \( {\theta }^{\prime } \in {\varepsilon }_{\rho }\mathbb{Z}/{p}^{n}\mathbb{Z}\left...
Proof. By assumption, \( 0 \neq \overline{{p}^{-a}\theta } \in {\bar{\varepsilon }}_{\rho }{\mathbb{F}}_{p}\left\lbrack \Delta \right\rbrack \) . Since this module is irreducible, \( \overline{{p}^{-a}\theta }{\bar{\varepsilon }}_{\rho }{\mathbb{F}}_{p}\left\lbrack \Delta \right\rbrack = {\bar{\varepsilon }}_{\rho }{\m...
Yes
Theorem 15.8. Let \( i \) be odd with \( 3 \leq i \leq p - 2 \) . If \( p \) divides the numerator of the Bernoulli number \( {B}_{p - i} \), then \( {\varepsilon }_{i}A \neq 0 \) .
Proof (assuming Theorem 15.7). Let \( {U}_{1} \) be the local units of \( \mathbb{Z}{\left\lbrack {\zeta }_{p}\right\rbrack }^{ + } \) that are congruent to 1 modulo the prime above \( p \) . Let \( {\bar{E}}_{1} \) be the closure of \( E \cap {U}_{1} \) and \( {\bar{C}}_{1} \) the closure of \( C \cap {U}_{1} \) .\n\n...
Yes
Lemma 15.9. (a) Assume \( \ell \nmid L \) . Then \( {N}_{\ell L/L}\alpha \left( {\ell L}\right) = \alpha {\left( L\right) }^{{\mathrm{{Frob}}}_{\ell } - 1} \), where \( {\mathrm{{Frob}}}_{\ell } \) is the Frobenius for \( \ell \) for the extension \( F\left( L\right) /\mathbb{Q} \) .
Proof. The norm for \( \mathbb{Q}\left( {{\zeta }_{m},{\zeta }_{\ell L}}\right) /\mathbb{Q}\left( {{\zeta }_{m},{\zeta }_{L}}\right) \) of \( 1 - {\zeta }_{m}^{j}{\zeta }_{\ell L} \) is\n\n\[ \mathop{\prod }\limits_{{k = 1}}^{{\ell - 1}}\left( {1 - {\zeta }_{m}^{j}{\zeta }_{L}{\zeta }_{\ell }^{k}}\right) = \frac{1 - {\...
Yes
Proposition 15.10. There exists \( {\beta }_{L} \in F{\left( L\right) }^{ \times } \) and \( \kappa \left( L\right) \in {F}^{ \times } \) such that\n\n\[ \n{D}_{L}\alpha \left( L\right) = \kappa \left( L\right) {\beta }_{L}^{M} \n\]\n\nand \( {\left( \left( \sigma - 1\right) {D}_{\ell }\alpha \left( L\right) \right) }^...
Proof. We claim that \( {D}_{L}\alpha \left( L\right) \in {\left( F{\left( L\right) }^{ \times }/F{\left( L\right) }^{\times M}\right) }^{G} \) (=the elements fixed by \( G \) ), where \( G = \operatorname{Gal}\left( {F\left( L\right) /F}\right) \) . The proof of the claim is by induction on the number of prime factors...
Yes
Lemma 15.11. There exists \( \beta \in F{\left( L\right) }^{ \times } \) such that \( c\left( \sigma \right) = {\beta }^{\sigma - 1} \) for all \( \sigma \in G \) .
Proof. By the theorem on linear independence of characters, there exists \( x \in F{\left( L\right) }^{ \times } \) such that \( y = \mathop{\sum }\limits_{{\sigma \in G}}c\left( \sigma \right) \sigma \left( x\right) \neq 0 \) . Let \( \tau \in G \) . The cocycle condition implies that\n\n\[ \n{\tau y} = \mathop{\sum }...
Yes
Proposition 15.12. Suppose \( \kappa \left( L\right) \equiv {s}^{a}\left( {\;\operatorname{mod}\;\lambda }\right) \) . Then the \( \lambda \) -adic valuation of \( \kappa \left( {\ell L}\right) \) satisfies\n\n\[ \n{v}_{\lambda }\left( {\kappa \left( {\ell L}\right) }\right) \equiv - a\;\left( {\;\operatorname{mod}\;M}...
Proof. From Proposition 15.10 and Lemma 15.5, we have\n\n\[ \n\left( {{\sigma }_{\ell } - 1}\right) {\beta }_{\ell L} = {\left( \left( {\sigma }_{\ell } - 1}\right) {D}_{\ell L}\alpha \left( \ell L\right) \right) }^{1/M} = {\left( \left( \ell - 1 - {N}_{\ell }\right) {D}_{L}\alpha \left( \ell L\right) \right) }^{1/M} \...
Yes
Lemma 15.13. Let \( \lambda ,\ell \), and \( s \) be as above, with \( \ell \equiv 1\left( {{\;\operatorname{mod}\;m}{ML}}\right) \) . Assume the ideal class \( \mathfrak{C} \) of \( \lambda \) is in \( {\varepsilon }_{x}A \) and also that the classes of the prime ideals of \( F \) dividing \( L \) are in \( {\varepsil...
Proof. Let \( \sigma \in \operatorname{Gal}\left( {F/\mathbb{Q}}\right) \) . Then \( s \) is a primitive root \( {\;\operatorname{mod}\;\sigma }\lambda \) . Let\n\n\[ \kappa \left( L\right) \equiv {s}^{{a}_{\sigma }}\;\left( {{\;\operatorname{mod}\;\sigma }\lambda }\right) \]\n\nWe then have \( {\sigma }^{-1}\kappa \le...
Yes