Complex quotients by nonclosed groups and their stratifications

ABSTRACT. We define the notion of complex stratification by quasifolds and show that such stratified spaces occur as complex quotients by certain nonclosed subgroups of tori associated to convex polytopes. The spaces thus obtained provide a natural generalization to the nonrational case of the notion of toric variety associated with a rational convex polytope. RÉSUMÉ . On définit la notion de stratification complexe de quasifolds et on montre que ces espaces stratifiés se réalizent comme quotients complexes par des sousgroupes non fermés de tores, associés aux polytopes convexes. Les espaces ainsi obtenus donnent une généralization naturelle, au cas non rationnel, de la notion de variété torique associée à un polytope convexe rationnel. Presented by Mark Goresky FRSC