English

Polyhedral realizations for crystal bases and Young walls of classical affine types

Quantum Algebra 2024-03-05 v1 Combinatorics Representation Theory

Abstract

For affine Lie algebra g\mathfrak{g} of type An1(1)A^{(1)}_{n-1}, Bn1(1)B^{(1)}_{n-1}, Cn1(1)C^{(1)}_{n-1}, Dn1(1)D^{(1)}_{n-1}, A2n2(2)A^{(2)}_{2n-2}, A2n3(2)A^{(2)}_{2n-3} or Dn(2)D^{(2)}_{n}, let B(λ)B(\lambda) and B()B(\infty) be the crystal bases of integrable highest weight representation V(λ)V(\lambda) and negative part Uq(g)U_q^-(\mathfrak{g}) of quantum group Uq(g)U_q(\mathfrak{g}). We consider the polyhedral realizations of crystal bases, which realize B(λ)B(\lambda) and B()B(\infty) as sets of integer points of some polytopes and cones in R\mathbb{R}^{\infty}. It is a natural problem to find explicit forms of the polytopes and cones. In this paper, we introduce pairs of truncated walls, which are defined as modifications of level 22-Young walls and describe inequalities defining the polytopes and cones in terms of level 11-proper Young walls and pairs of truncated walls. As an application, we also give combinatorial descriptions of εk\varepsilon_k^*-functions on B()B(\infty) in terms of Young walls and truncated walls.

Keywords

Cite

@article{arxiv.2403.01190,
  title  = {Polyhedral realizations for crystal bases and Young walls of classical affine types},
  author = {Yuki Kanakubo},
  journal= {arXiv preprint arXiv:2403.01190},
  year   = {2024}
}

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45 pages