Title: Equivariant CW-Complexes and the Orbit Category


Authors: Ian Hambleton, Semra Pamuk, and Erg\"un Yal\c c\i n


Status: Revised version, to appear in Comment. Math. Helv.


Address 1: 
Department of Mathematics, McMaster University,
Hamilton, Ontario L8S 4K1, Canada

Address 2: 
Department of Mathematics, McMaster University,
Hamilton, Ontario L8S 4K1, Canada

Address 3: 
Department of Mathematics, Bilkent University,
06800 Bilkent, Ankara, Turkey


Abstract:
We give a general framework for studying $G$-CW-
complexes via 
the orbit category. As an application we show that the symmetric

group $G=S_5$ admits a finite $G$-CW-complex $X$ homotopy 
equivalent 
to a sphere, with cyclic isotropy subgroups.