Inducing graph invariants from the universal gl-weight system
Sergei Lando (HSE University, Skolkovo Institute of Science and Technology)
Abstract: Weight systems, which are functions on chord diagrams satisfying certain 4- term relations, appear naturally in Vassiliev's theory of nite type knot invariants. In particular, a weight system can be constructed from any nite dimensional Lie algebra endowed with a nondegenerate invariant bilinear form. Recently, M. Kazarian suggested to extend the gl(N)-weight system from chord diagrams (treated as involutions without xed point) to arbitrary permutations, which led to a recurrence formula allowing for an eective computation of its values, elaborated by Zhuoke Yang. In turn, the recurrence helped to unify the gl(N) weight systems, for N = 1, 2, 3, . . . , into a universal gl-weight system. The latter takes values in the ring of polynomials C[N][C1, C2, . . . ] in in nitely many variables C1, C2, . . . (Casimir elements), whose coe cients are polynomials in N. The universal gl-weight system carries a lot of information about chord diagrams and intersection graphs. The talk will address the question which graph invariants can be extracted from it. We will discuss the interlace polynomial, the enhanced skew-characteristic polynomial, and the chromatic polynomial. In particular, we show that the interlace polynomial of the intersection graphs can be obtained by a speci c substitution for the variables N, C1, C2, . . . . This allows one to extend it from chord diagrams to arbitrary permutations. Questions concerning other graph and delta-matroid invariants and their presumable extensions will be formulated. The talk is based on a work of the speaker and a PhD student Nadezhda Kodaneva.
mathematical physicsdynamical systemsquantum algebrarepresentation theorysymplectic geometry
Audience: general audience
BIMSA Integrable Systems Seminar
Series comments: The aim is to bring together experts in integrable systems and related areas of theoretical and mathematical physics and mathematics. There will be research presentations and overview talks.
Audience: Graduate students and researchers interested in integrable systems and related mathematical structures, such as symplectic and Poisson geometry and representation theory.
The zoom link will be distributed by mail, so please join the mailing list if you are interested in attending the seminar.
| Organizers: | NiŃolai Reshetikhin, Andrii Liashyk, Ivan Sechin, Andrey Tsiganov* |
| *contact for this listing |