**BİLKENT
ALGEBRA **

TOPOLOGY SEMINAR

**"****Ghost Numbers of Group Algebras****"**

By

# FATMA ALTUNBULAK AKSU

# (Çankaya University)

**Abstract:** A ghost in the stable module category of a finite group G is a map
between modular representations of G which induces a trivial map on Tate cohomology. The Freyd's
generating hypothesis (GH) for the stable module category of G is the statement
that every ghost between finitely generated modular representations of G
factors through a projective module. In this talk, we discuss p-groups for
which GH fails and then we introduce the ghost number of a group algebra which
measures the degree of the failure of GH.

**Date: ****Monday, March 4, 2013**

**Time: ****13.40-14.30**

**Place: ****Mathematics Seminar Room,
SA-141**

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**All are most cordially invited.**

Tea and cookies will be served after the talk.