diff --git a/article_de_rham_cyclic.bbl b/article_de_rham_cyclic.bbl index 334e3eb..f4518a9 100644 --- a/article_de_rham_cyclic.bbl +++ b/article_de_rham_cyclic.bbl @@ -1,5 +1,13 @@ \begin{thebibliography}{10} +\bibitem{Alperin_local_rep} +J.~L. Alperin. +\newblock {\em Local representation theory}, volume~11 of {\em Cambridge + Studies in Advanced Mathematics}. +\newblock Cambridge University Press, Cambridge, 1986. +\newblock Modular representations as an introduction to the local + representation theory of finite groups. + \bibitem{Bleher_Camacho_Holomorphic_differentials} F.~M. Bleher and N.~Camacho. \newblock Holomorphic differentials of {K}lein four covers. diff --git a/article_de_rham_cyclic.synctex.gz b/article_de_rham_cyclic.synctex.gz index e06555e..47a6ef8 100644 Binary files a/article_de_rham_cyclic.synctex.gz and b/article_de_rham_cyclic.synctex.gz differ diff --git a/article_de_rham_cyclic.tex b/article_de_rham_cyclic.tex index d17e436..c979f5d 100644 --- a/article_de_rham_cyclic.tex +++ b/article_de_rham_cyclic.tex @@ -560,9 +560,20 @@ Let $X$ be a curve with an action of $G$ and write $Y := X/H$. For any $k[C]$-mo is uniquely determined by the $k[C]$-structure of $T^1 M, \ldots, T^{p^n} M$. \end{Lemma} \begin{proof} - This is basically \cite[proof of Theorem~1.1]{Bleher_Chinburg_Kontogeorgis_Galois_structure}. We sketch the proof for reader's convenience. Recall that if $U$ is an indecomposable $k[G]$-module - then $U^{\sigma} := \ker(\sigma - 1)$ (the socle of $U$) is a one-dimensional - $k[C]$-module. Thus it comes from a character $\chi_U \in \wh{C} := \Hom(C, \CC)$. + This is basically \cite[proof of Theorem~1.1]{Bleher_Chinburg_Kontogeorgis_Galois_structure}. We sketch the proof for reader's convenience. + Assume that $G$ is a finite group with a normal cyclic $p$-Sylow subgroup $H = \langle \sigma \rangle \cong \ZZ/p^n$. Let $C := G/H$. + Recall that if $U$ is an indecomposable $k[G]$-module + then $U^{\sigma} := \ker(\sigma - 1)$ (the socle of $U$) is an indecomposable + $k[C]$-module. It turns out that the map + % + \begin{align*} + \Indec(k[G]) \to \Indec(k[C]) \times \{ 1, \ldots, p^n \}\\ + U \mapsto (U^{\sigma}, \frac{\dim_k U}{\dim_k U^{\sigma}}) + \end{align*} + % + is a bijection (cf. \cite[p. 35--37, 42 -- 43]{Alperin_local_rep}). We write + $\mc V(M, i)$ for the $k[G]$-module corresponding to a pair $(M, i) \in \Indec(k[C]) \times \{ 1, \ldots, p^n \}$. + Thus it comes from a character $\chi_U \in \wh{C} := \Hom(C, \CC)$. It turns out that the map % \[ @@ -672,7 +683,7 @@ Let $X$ be a curve with an action of $G$ and write $Y := X/H$. For any $k[C]$-mo % \begin{align} \mc T^1 \mc M &\cong T^1 \mc M \oplus T^2 \mc M \oplus (T^2 \mc M)^{\chi^{-1}} \oplus \ldots \oplus (T^2 \mc M)^{\chi^{-(p - 2)}} \label{eqn:decomposition_of_mc_T1}\\ - \mc T^i \mc M &\cong T^2 \mc M \oplus \ldots \oplus (T^2 \mc M)^{\chi^{-(p-1)}} \quad \textrm{ for } 2 \le i \le p^n - p^{n-1}. \label{eqn:decomposition_of_mc_Ti} + \mc T^i \mc M &\cong T^2 \mc M \oplus \ldots \oplus (T^2 \mc M)^{\chi^{-(p-1)}} \quad \textrm{ for } 2 \le i \le p^{n-1}. ???? \label{eqn:decomposition_of_mc_Ti} \end{align} % Thus, since by induction hypothesis $\mc T^i \mc M$ is determined by higher ramification data,