 Harish-Chandra restriction (source code)

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= Harish-Chandra restriction
{c}
{title2=$\,{}^*R_{L\subset P}^G(V)=V^{U^F}$}

Restriction first views a $G^F$-module as a $P^F$-module, then takes the subspace fixed by the unipotent radical. The resulting $L^F$-module is adjoint to <Harish-Chandra induction> by ordinary <Frobenius reciprocity>. Over characteristic zero, averaging makes invariants exact and identifies them with coinvariants.

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