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Character formulas for general Kac-Moody algebras. (Formules de caractères pour les algèbres de Kac-Moody générales.) (French) Zbl 0683.17010
Centre National de la Recherche Scientifique (France). Astérisque, 159-160. Paris: Société Mathématique de France. 267 p. FF 185.00; $ 31.00 (1988).
The author extends Demazure’s character formula to any Kac-Moody algebra (not necessarily symmetrizable). From this, using an argument of G. Heckman, he gets the Weyl character formula. Underlying these results, there is the identification of the characters with some Euler-Poincaré characteristic dimensions and the proof of vanishing theorems for the cohomology of semi-ample line bundles over the Schubert varieties. This machinery also allows him to prove a generalization of the Bott-Borel- Weyl theorem and Kempf’s theorem, as well as some properties of the Schubert varieties.
Reviewer: F.Levstein

17B67 Kac-Moody (super)algebras; extended affine Lie algebras; toroidal Lie algebras
17-02 Research exposition (monographs, survey articles) pertaining to nonassociative rings and algebras
17B10 Representations of Lie algebras and Lie superalgebras, algebraic theory (weights)
14M15 Grassmannians, Schubert varieties, flag manifolds
17B65 Infinite-dimensional Lie (super)algebras
14F99 (Co)homology theory in algebraic geometry