English

Permutations with Verma Multiplicities $[M(p):L(q)] \geq 2$

Combinatorics 2026-07-21 v1 Representation Theory

Abstract

We consider permutations qq in the symmetric group SnS_n whose Verma multiplicities in the principal block of O(sln)\mathcal{O}(\mathfrak{sl}_n) satisfy [M(p):L(q)]2[M(p):L(q)] \geq 2. We present a construction along with a diagrammatic visualization, showing how permutations in SnS_n with this property generate a family of permutations in Sn+1S_{n+1} that share the same multiplicity property. While the method does not recover all such permutations in Sn+1S_{n+1}, it systematically generates many new examples. In addition, we present all permutations in S5S_5 with [M(id):L(q)]2[M(\mathrm{id}):L(q)] \geq 2 in a Bruhat diagram and describe all permutations in S6S_6 and S7S_7 with non-simple Verma multiplicities.

Keywords

Cite

@article{arxiv.2607.19112,
  title  = {Permutations with Verma Multiplicities $[M(p):L(q)] \geq 2$},
  author = {Daiva Pucinskaite},
  journal= {arXiv preprint arXiv:2607.19112},
  year   = {2026}
}