Betti numbers of monomial ideals fixed by permutations of the variables

Satoshi Murai (Waseda University)

25-Mar-2021, 22:00-23:30 (3 years ago)

Abstract: Let R_n be the polynomial ring with n variables over a field K. We consider the natural action of the n-th symmetric group S_n to R_n. In this talk, I will mainly talk about the following problem: Fix monomials u_1,\dots,u_m and consider the ideal I_n of R_n generated by the S_n-orbits of these monomials. How the Betti numbers of I_n change when n increases? I will explain that there is a simple way to determine non-zero positions of the Betti table of I_n when n is sufficiently large. I also explain that we can determine the Betti numbers of I_n by considering the S_n-module structure of Tor_i(I_n,K).

The above problem is motivated by recent studies of algebraic properties of S_n-invariant ideals and is inspired by studies of Noetherianity up to symmetry. I will explain this motivation and basic combinatorial properties of S_n-invariant ideals in the first part of the talk. This talk includes a joint work with Claudiu Raicu.

commutative algebra

Audience: researchers in the topic


Fellowship of the Ring

Series comments: Description: National Commutative Algebra Seminar

You have to register to attend the seminar; the registration link is on the webpage. But you only have to register once. Once you register for a seminar, your registration will be carried over (in theory!) to future seminars.

Organizers: Srikanth B. Iyengar*, Karl E. Schwede
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