Basic Sets for the Double Covering Groups of the Symmetric and Alternating Groups in Odd Characteristic

Acknowledgements. Part of this work was done at the CIRM in Luminy during a research in pairs stay. The authors wish to thank the CIRM gratefully for their financial and logistical support. The first author is supported by Agence Nationale de la Recherche Projet ACORT ANR-12-JS01-0003. The second author also acknowledges financial support from the Engineering and Physical Sciences Research Council grant Combinatorial Representation Theory EP/M019292/1. The authors wish to thank the referee for several helpful suggestions.Peer reviewedPostprin