Partition into heapable sequences, heap tableaux and a multiset extension of Hammersley’s process

Gabriel Istrate

(joint work with Cosmin Bonchis)

4 March 2015

Abstract

We investigate partitioning of integer sequences into heapable subsequences (previously defined and established by Mitzenmacher et al.). We show that an extension of patience sorting computes the decomposition into a minimal number of heapable subsequences (MHS). We connect this parameter to an interactive particle system, a multiset extension of Hammersley’s process, and investigate its expected value on a random permutation. In contrast with the (well studied) case of the longest increasing subsequence, we bring experimental evidence that the correct asymptotic scaling is (1+\sqrt{5})/2\cdot \ln(n). Finally we give a heap-based extension of Young tableaux, prove a hook inequality and an extension of the Robinson-Schensted correspondence.