**ALGEBRAIC
TOPOLOGY SEMINAR**

#

“Almost complex substructures
on spheres equivariant under

semifree group actions”

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TURGUT ONDER

(METU)

Abstract: Let G be a finite group and V
be unitary representation of G. We will first give a brief review of the
earlier results about the existence of a G-invariant subbundle of the tangent
bundle of the unit sphere S(V) admitting a G-equivariant complex
structure. Then we will show that the sufficient conditions found earlier for
the existence of such subbundles (and equivariant complex structures on them)
are also necessary for at least a large group of semifree group actions. The
proof uses Bredon Cohomology and Equivariant K-theory.

Date : March 30, 2009 (Monday)

Time : 13.40-15.30

Place: Department of Mathematics SAZ-02