English

Affine transformations of a Leonard pair

Rings and Algebras 2007-05-23 v1 Combinatorics

Abstract

Let KK denote a field and let VV denote a vector space over KK with finite positive dimension. We consider an ordered pair of linear transformations A:VVA : V \to V and A:VVA^* : V \to V that satisfy (i) and (ii) below: (i) There exists a basis for VV with respect to which the matrix representing AA is irreducible tridiagonal and the matrix representing AA^* is diagonal. (ii) There exists a basis for VV with respect to which the matrix representing AA^* is irreducible tridiagonal and the matrix representing AA is diagonal. We call such a pair a Leonard pair on VV. Let xx, cc, xx^*, cc^* denote scalars in KK with xx, xx^* nonzero, and note that xA+cIxA+cI, xA+cIx^*A^* + c^*I is a Leonard pair on VV. We give necessary and sufficient conditions for this Leonard pair to be isomorphic to the Leonard pair AA, AA^*. We also give necessary and sufficient conditions for this Leonard pair to be isomorphic to the Leonard pair AA^*, AA.

Keywords

Cite

@article{arxiv.math/0611783,
  title  = {Affine transformations of a Leonard pair},
  author = {Kazumasa Nomura and Paul Terwilliger},
  journal= {arXiv preprint arXiv:math/0611783},
  year   = {2007}
}

Comments

33 pages

R2 v1 2026-07-22T17:46:55.966Z