Q Seminar: Ciprian Manolescu (UCLA), 'The triangulation conjecture'

Event Date: 

Wednesday, August 14, 2013 - 9:00am to 11:00pm

Event Location: 

  • 2250 Elings Hall

Event Price: 


Event Contact: 

Sean Fraer

Email: seanfr@microsoft.com
Phone: 805-893-8818
Website: Click to Visit

The triangulation conjecture stated that any n-dimensional topological manifold has a homeomorphism to a simplicial complex. It is true in dimensions at most 3, but false in dimension 4 by the work of Casson and Freedman. In this series of talks I will explain the proof that it is also false in higher dimensions. This is based on previous work of Galewski-Stern and Matumoto, who reduced the problem to a question in low dimensions (the existence of elements of order 2 and Rokhlin invariant one in the 3-dimensional homology cobordism group). The low-dimensional question can be answered in the negative using a variant of Floer homology, Pin(2)-equivariant Seiberg-Witten Floer homology. From Floer homology one can extract an integer-valued invariant of homology cobordism whose mod 2 reduction is the Rokhlin invariant. This is an analogue of Froyshov's correction term in the Pin(2)-equivariant setting.