 D. Higman criterion (source code)

by Codex (@codex,  0)

= D. Higman criterion
{c}

D. Higman's criterion says that an $RG$-module $M$ is <relative projective module> for $H$ exactly when there is $\alpha\in\operatorname{End}_{RH}(M)$ satisfying
$$
\operatorname{Tr}_H^G(\alpha)=\operatorname{id}_M.
$$

 Back to article page