Module of covariants explained

In algebra, given an algebraic group G, a G-module M and a G-algebra A, all over a field k, the module of covariants of type M is the

A ^{G} -module(M ⊗ _{k} A) ^{G.}

where

- ^{G} refers to taking the elements fixed by the action of G; thus, A ^{G} is the ring of invariants of A.

See also

• Local cohomology

References

• M. Brion, Sur les modules de covariants, Ann. Sci. École Norm. Sup. (4) 26 (1993), 1 21.
• M. Van den Bergh, Modules of covariants, Proceedings of the International Congress of Mathematicians, Vol. 1, 2 (Zurich, 1994), Birkhauser, Basel, pp. 352–362, 1995.