Some algebra related to $P$-and $Q$-polynomial association schemes

Tatsuro Ito, Kenichiro Tanabe, Paul Terwilliger

Let $K$ denote a field, and let $V$ denote a vector space over $K$ with finite positive dimension. Consider a pair of linear transformations $A:V\to V$ and $A^{\ast }:V\to V$ that satisf…