Four-dimensional topology from Khovanov homology
Four-dimensional topology from Khovanov homology
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Robert Lipshitz, Minerva Distinguished Visitor & University of Oregon
Fine Hall 314
Livestream: https://youtube.com/live/l8sNFbo8uVg
We will apply Khovanov homology to the existence question for surfaces. We will start by showing the Rasmussen’s invariant obstructs knots from bounding low-genus surfaces, and outline some pain-free proofs that this obstruction is nontrivial. We will then combine these results with Freedman’s theorem from the previous talk (and a few related black-boxed results) to deduce that R4 admits nonstandard smooth structures.