Resumen de Alternating subgroups of Coxeter groups and their spinor extensions

O. V. Ogievetsky, Loïc Poulain d'Andecy

• Let G be a discrete Coxeter group, G+ its alternating subgroup and �G+ the spinor cover of G+. A presentation of the groups G+ and �G+ is proved for an arbitrary Coxeter system (G, S); the generators are related to edges of the Coxeter graph. Results of the Coxeter�Todd algorithm � with this presentation � for the chains of alternating groups of types A, B and D are given.