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arXiv · 2209.11986

Naturality and innerness for morphisms of compact groups and (restricted) Lie algebras

Alexandru Chirvasitu
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Abstract

An extended derivation (endomorphism) of a (restricted) Lie algebra $L$ is an assignment of a derivation (respectively) of $L'$ for any (restricted) Lie morphism $f:L\to L'$, functorial in $f$ in the obvious sense. We show that (a) the only extended endomorphisms of a restricted Lie algebra are the two obvious ones, assigning either the identity or the zero map of $L'$ to every $f$; and (b) if $L$ is a Lie algebra in characteristic zero or a restricted Lie algebra in positive characteristic, then $L$ is in canonical bijection with its space of extended derivations (so the latter are all, in a sense, inner). These results answer a number of questions of G. Bergman. In a similar vein, we show that the individual components of an extended endomorphism of a compact connected group are either all trivial or all inner automorphisms.

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Alexandru Chirvasitu. 2022-09-24. Naturality and innerness for morphisms of compact groups and (restricted) Lie algebras. https://arxiv.org/abs/2209.11986

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