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SUMMARY:Pretzel knots with unknotting number one - Julian Gibbons (Imperia
 l)
DTSTART:20120207T150000Z
DTEND:20120207T160000Z
UID:TALK35272@talks.cam.ac.uk
CONTACT:Dr Andras Juhasz
DESCRIPTION:The unknotting number u(K) of a knot is a deceptively difficul
 t invariant to compute. In this talk\, I will explain how various obstruct
 ions to u(K) = 1 can be applied to pretzels\, and provide a partial classi
 fication of such knots with u(K) = 1. These techniques will be a mixture o
 f classical theory and the more recent Heegaard Floer homology by Ozsvath 
 and Szabo.
LOCATION:MR15
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