Some matrices associated with the split decomposition for a Q-polynomial distance-regular graph
Abstract
We consider a -polynomial distance-regular graph with vertex set and diameter . For we define a direct sum decomposition of the standard module , called the --split decomposition. For this decomposition we compute the complex conjugate and transpose of the associated primitive idempotents. Now fix such that and assume has classical parameters with . Under this assumption Ito and Terwilliger displayed an action of the -tetrahedron algebra on the standard module of . To describe this action they defined eight matrices in , called \begin{eqnarray*} \label{eq:list} A,\quad A^*,\quad B,\quad B^*, \quad K,\quad K^*,\quad \Phi,\quad \Psi. \end{eqnarray*} For each matrix in the above list we compute the transpose and complex conjugate. Using this information we compute the transpose and complex conjugate for each generator of on .
Cite
@article{arxiv.0710.4383,
title = {Some matrices associated with the split decomposition for a Q-polynomial distance-regular graph},
author = {Joohyung Kim},
journal= {arXiv preprint arXiv:0710.4383},
year = {2007}
}