"What is ... a van Kampen obstruction cocycle" -- Isaac Mabillard (IST Austria)

16.01.2015 | 16:00


"What is ... a van Kampen obstruction cocycle"  -- Isaac Mabillard (IST
Austria)

16:00, Friday, January 16, 2015
@TU MA 313
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ABSTRACT:
The Kuratowski theorem provides a nice criterion for graph planarity, ie,
to decide whether a simplicial 1-complex can be embedded into R^2.

A natural generalization of the problem is to find a criterion to decide
whether a simplicial n-complex K can be embedded into R^{2n}. This is what
the van Kampen obstruction cocycle gives us. By using standard tricks in
PL topology, one can show that K is embeddable if and only if (the class
of) its cocycle is zero.

This is (maybe?) surprising because embeddability is a geometric question,
whereas a cocycle is an algebraic object, but it still carries enough
information to solve the geometric problem.
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Zeit & Ort

16.01.2015 | 16:00

@TU MA 313
www.math.fu-berlin.de/w/Math/WhatIsSeminar