## EVENT DETAILS AND ABSTRACT

**Topology Seminar**
**Title:** The cyclic (co)bar construction on A-infinity objects and THH

**Speaker:** Vigleik Angeltveit

**Speaker Info:** MIT

**Brief Description:**

**Special Note**: **Note the time.**

**Abstract:**

A classical result of Stasheff says that one can define the bar
construction on an A-infinity H-space using a certain family of
polyhedra called Stasheff associahedra. I will show how one can define
the cyclic bar and cobar construction in a similar way, using another
family of polyhedra called cyclohedra. I will then use this to define
THH of an A-infinity ring spectrum, and explain how the A-infinity
structure is responsible for extensions in the canonical spectral
sequences calculating the homotopy groups of THH.

**Date:** Monday, January 16, 2006

**Time:** 3pm

**Where:** Lunt 104

**Contact Person:** Prof. Paul Goerss

**Contact email:** pgoerss@math.northwestern.edu

**Contact Phone:** 847-491-8544

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