============================================================== File: odd4.dvi Author 1: John Maginnis Address: Mathematics Department, Kansas State University, 137 Cardwell Hall, Manhattan, Kansas 66506 Author 2: Silvia Onofrei Address: Mathematics Department, Kansas State University, 137 Cardwell Hall, Manhattan, Kansas 66506 Title: On fixed point sets and Lefschetz modules for sporadic simple groups Abstract: We consider 2-local geometries and other subgroup complexes for sporadic simple groups. For six groups, the fixed point set of a noncentral involution is shown to be equivariantly homotopy equivalent to a standard geometry for the component of the centralizer. For odd primes, fixed point sets are computed for sporadic groups having an extraspecial Sylow p-subgroup of order p^3, acting on the complex of those p-radical subgroups containing a p-central element in their centers. Vertices for summands of the associated reduced Lefschetz modules are described. Preprint, January 2008