Speaker: Prof. Dennis Stanton (University of Minnesota, U.S.A.) Talk 1: Algorithmic Combinatorics Seminar Talk (RISC Colloquium Talk) Time and Location: Wednesday, March 25, 2015 2:00 pm, Seminar room castle, RISC, Hagenberg Title: Another (q,t)-world ABSTRACT: A well studied (q,t)-analogue of symmetric functions are the Macdonald polynomials. In this talk I will survey another (q,t)-analogue, where q is a prime power from a finite field and t is an indeterminate. Analogues of facts about the symmetric group S_n are given for GL_n(F_q), including (1) counting factorizations of certain elements into reflections, (2) combinatorial properties of appropriate (q,t)-binomial coefficients, (3) Hilbert series for invariants on polynomial rings. Some new conjectured explicit Hilbert series of rings of invariants are given. This is joint work with Joel Lewis and Vic Reiner. --------------------------------------------------------------------------- Talk 2: SFB Talk (Algorithmic and Enumerative Combintorics) Time and Location: Thursday, March 26, 2015 2:00 pm, Seminar room pond, RISC, Hagenberg TITLE: Problems I cannot do - that people at RISC hopefully could do ABSTRACT: I will discuss open problems in enumeration, including partitions, and special functions. This will include the Rogers-Ramanujan identities, Gessel paths, the Omega operator, generalized super Catalan numbers, very well poised series, finite difference calculus, finite fields, and homology questions.