The weights for a finite group G with respect to a prime number p where introduced by Jon Alperin, in order to formulate his celebrated conjecture affirming that that the number of G-conjugacy classes of weights of G coincides with the number of isomorphism classes of simple kG-modules, where k is an algebraically closed field of characteristic p. Thirty years ago, Tetsuro Okuyama already proved that in the class of p-solvable groups this conjecture holds. In this paper, for the p-solvable groups, on the one hand we exhibit a natural bijection - namely compatible with the action of the group of outer automorphisms of G - between the sets of isomorphism classes of simple G-modules M and of G-conjugacy classes of weights (R,Y), up to the choice of a polarization. On the other hand, we determine the relationship between a multiplicity module of M and Y. In an Appendix, we show that the bijection defined by Gabriel Navarro for the groups of odd order coincides with our bijection for a particular choice of the polarization.
有限群$G$称为对合Yang-Baxter(IYB),如果对某个$M$-模$\mathbb Z G$存在一个双射1-上圈$χ: G \longrightarrow M$.已知每个IYB-群都是可解的,但其逆是否成立仍然是一个悬而未决的问题。IYB属性的一个特征是在补充集合$1-G$的增广理想$ω\mathbb Z G$中存在一个理想$I$,这导致了一些猜测,即可能与$\mathbb Z G$的同构问题有关。本文证明了:若$N$是第二类幂零群,且$H$是与$N$阶互素的IYB-群,则$N\rtimes H$是IYB.类的群体,可以得到这种方式(因此是IYB)包含特别是赫特韦克著名的反例同构猜想以及所有的子群。然后,我们研究什么是IYB结构的Hertweck的反例看起来像具体的。