Timeline for Homological vs. cohomological dimension of a group/space
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 21, 2023 at 20:40 | comment | added | Jeremy Rickard | @Carl-FredrikNybergBrodda $G/A$ is the set of left cosets of $A$ in $G$, and $\mathbb{Z}[G/A]$ is the free abelian group with basis $G/A$, which is a left $\mathbb{Z}G$-module via the action of $G$ on $G/A$ by left multiplication. | |
| Apr 21, 2023 at 18:04 | comment | added | Carl-Fredrik Nyberg Brodda | What does the notation $\mathbb{Z}[G/A]$ mean here? Since $A$ is not necessarily normal I’m guessing it refers to something other than the quotient. | |
| Jul 15, 2015 at 21:54 | comment | added | Fernando Muro | This actually answers Q3 not only for $X=BG$ but for any $X$ since the canonical map $X\rightarrow B\pi_1(X)$ induces an isomorphism on $H^1$ with coefficients in any $\pi_1(X)$-module. | |
| Jul 15, 2015 at 10:21 | history | answered | Jeremy Rickard | CC BY-SA 3.0 |