A q-weighted version of the Robinson-Schensted algorithm

TL;DR

This paper introduces a q-weighted, randomized version of the Robinson-Schensted algorithm that connects to q-Whittaker functions, providing new insights into q-TASEP particle systems and related tableau evolutions.

Contribution

It develops a novel q-insertion algorithm that generalizes Robinson-Schensted, linking it to q-Whittaker functions and q-TASEP, and explores new tableau evolution processes.

Findings

The q-insertion algorithm reduces to classical Robinson-Schensted when q=0.

Distribution of tableaux pairs relates to q-Whittaker functions.

Provides a new framework for analyzing q-TASEP dynamics.

Abstract

We introduce a q-weighted version of the Robinson-Schensted (column insertion) algorithm which is closely connected to q-Whittaker functions (or Macdonald polynomials with t=0) and reduces to the usual Robinson-Schensted algorithm when q=0. The q-insertion algorithm is `randomised', or `quantum', in the sense that when inserting a positive integer into a tableau, the output is a distribution of weights on a particular set of tableaux which includes the output which would have been obtained via the usual column insertion algorithm. There is also a notion of recording tableau in this setting. We show that the distribution of weights of the pair of tableaux obtained when one applies the q-insertion algorithm to a random word or permutation takes a particularly simple form and is closely related to q-Whittaker functions. In the case $0\le q<1$, the q-insertion algorithm applied to a random word also provides a new framework for solving the q-TASEP interacting particle system introduced (in the language of q-bosons) by Sasamoto and Wadati (1998) and yields formulas which are equivalent to some of those recently obtained by Borodin and Corwin (2011) via a stochastic evolution on discrete Gelfand-Tsetlin patterns (or semistandard tableaux) which is coupled to the q-TASEP process. We show that the sequence of P-tableaux obtained when one applies the q-insertion algorithm to a random word defines another, quite different, evolution on semistandard tableaux which is also coupled to the q-TASEP process.