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A study of augmentation varieties associated to Legendrian knots/tangles

Student-Run Geometry/Topology Seminar

Speaker: Tao Su, UC Berkeley
Related Webpage: https://math.berkeley.edu/~taosu/
Location: 2112 MSB
Start time: Thu, May 24 2018, 2:10PM



We give a tangle approach in the study of Legendrian knots in contact three-space. This includes Legendrian isotopy invariants: ruling polynomials, and Chekanov-Eliashberg or Legendrian Contact Homology differential graded algebras (LCH DGAs) for Legendrian tangles, generalizing those of Legendrian knots.

By studying the "representation varieties (of rank 1)" of the LCH DGAs, called augmentation varieties, we also see that the points-counting/weight (or virtual Poincare) polynomials of the varieties give the ruling polynomials. The tangle approach in particular provides a generalization and a more natural proof to some previous known results of M.Henry and D.Rutherford.

Time permitting, I will also mention some more aspects of the study of augmentation varieties.