English

The number of inversions of permutations with fixed shape

Combinatorics 2022-01-03 v2 Probability

Abstract

The Robinson-Schensted correspondence can be viewed as a map from permutations to partitions. In this work, we study the number of inversions of permutations corresponding to a fixed partition λ\lambda under this map. Hohlweg characterized permutations having shape λ\lambda with the minimum number of inversions. Here, we give the first results in this direction for higher numbers of inversions. We give explicit conjectures for both the structure and the number of permutations associated to λ\lambda where the extra number of inversions is less than the length of the smallest column of λ\lambda. We prove the result when λ\lambda has two columns.

Keywords

Cite

@article{arxiv.1712.10122,
  title  = {The number of inversions of permutations with fixed shape},
  author = {Arvind Ayyer and Naya Banerjee},
  journal= {arXiv preprint arXiv:1712.10122},
  year   = {2022}
}

Comments

20 pages, 2 figures, several minor improvements, final version