Reduced word enumeration, complexity, and randomization

A reduced word of a permutation w is a minimal length expression of w as a product of simple transpositions. We examine formulas and (randomized) algorithms for their enumeration. In particular, we prove that the Edelman-Greene statistic, defined by S. Billey-B. Pawlowski, is typically exponentially large. This implies a result of B. Pawlowski, that it has exponentially growing expectation. Our result is established by a formal run-time complexity analysis of A. Lascoux-M.-P. Schützenberger’s transition algorithm. The more general problem of Hecke word enumeration, and its closely related question of counting set-valued standard Young tableaux, is also investigated. The latter enumeration problem is further motivated by work on Brill-Noether varieties due to M. Chan-N. Pflueger and D. Anderson-L. Chen-N. Tarasca. We also state some related problems about counting compu-tational complexity.