Let $M$ be a $G$-module and let $\psi\colon G\to M$ be a map. What is usually meant with the symbol $\psi_{\sigma}$ where $\sigma\in G$ in the group cohomology context? I am using the appendix from J.Silverman arithmetic of elliptic curves. Thanks.
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1Can you give a page number? No one wants to go flipping through entire sections looking for a specific notation. – Future Jan 22 '16 at 13:48
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First page in the group cohomology appendix. Did not think that a first page notation could be so non-standard that people would need a more specific context to identify it. This is why I didn't mention pages. Sorry though. Since I have no knowledge yet about this, I thought this was like "what $A^{T}$ means in matrix theory?", where no context is fully needed – Shoutre Jan 23 '16 at 01:38
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I checked that page and checked the next page to be sure, and I did not see any instances of what you are describing. I am looking at Appendix B pg. 415-416 of the 2nd ed. – Future Jan 23 '16 at 01:49
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I really did not think it would be so hard to find and that's why I did not make a more precise question. I apologize for that and I really appreciate your patience in not dropping the question. Perhaps I should mention that I changed the greek letter that was used because I did not know how to write it in TeX so I used $\psi$. Now, a more explicit description: Its in the $1$-cocycles definition: write $C^{1}(G,M)$ for maps $\xi\colon G\to M$ and then define $H^{1}(G,M)={\xi\in C^{1}(G,M):|:\xi_{\tau\sigma}=\xi_{\sigma}^{\tau}+\xi_{\tau}:\forall \sigma,\tau\in G}.$ – Shoutre Jan 23 '16 at 12:20
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My question is about these $\xi_{\tau}$, $\xi_{\sigma}^{\tau}$. What do they mean? And again, I apologize for the inconvenience. – Shoutre Jan 23 '16 at 12:23