As we know, the Frattini subgroup of a finite group G can not contain a Sylow subgroup of G, but if we want to prove this, we need the Schur-Zassenhaus theorem. What I want to know is if there is a more elementary proof of this.
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Alexander Gruber
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user94782
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1The Schur-Zassenhaus proof is given at http://math.stackexchange.com/a/766031/583 – Jack Schmidt Apr 30 '14 at 02:56
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I assume using representation theory is cheating? – Jack Schmidt Apr 30 '14 at 03:04
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Presumably this doesn't count as S-Z-free:
Let $P \leq \Phi(G)$ be a Sylow $p$-subgroup of $G$. Since $\Phi(G)$ is nilpotent (by the Frattini argument), $P$ is characteristic in $\Phi(G)$, so $P$ is characteristic in $G$ as well. By induction, we may assume $P$ is elementary abelian (mod out by $\Phi(P) \unlhd G$ to get a smaller example). But then, we have a non-split extension of $G/P$ by $P$, contradicting Maschke's theorem that $P$ is an injective $G/P$-module so that $H^2(G/P,P)=0$.
Jack Schmidt
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