
arXiv: 0706.1065
Let $K$ denote an algebraically closed field with characteristic 0 and let $V$ denote a vector space over $K$ with finite positive dimension. Let $A,A^*$ denote a tridiagonal pair on $V$ with diameter $d$. We say that $A,A^*$ has Krawtchouk type whenever the sequence $\lbrace d-2i\rbrace_{i=0}^d$ is a standard ordering of the eigenvalues of $A$ and a standard ordering of the eigenvalues of $A^*$. Assume $A,A^*$ has Krawtchouk type. We show that there exists a nondegenerate symmetric bilinear form $< , >$ on $V$ such that $= < u,Av>$ and $= < u,A^*v>$ for $u,v\in V$. We show that the following tridiagonal pairs are isomorphic: (i) $A,A^*$; (ii) $-A,-A^*$; (iii) $A^*,A$; (iv) $-A^*,-A$. We give a number of related results and conjectures.
20 pages
tetrahedron Lie algebra, Numerical Analysis, 05E30,15A21, Eigenvalues, singular values, and eigenvectors, Algebra and Number Theory, Canonical forms, reductions, classification, tridiagonal pair, eigenvalues, Mathematics - Rings and Algebras, Tetrahedron Lie algebra, 33C45, Tridiagonal pair, 33C45; 05E30,15A21, Krawtchouk type tridiagonal pair, Rings and Algebras (math.RA), Leonard pair, FOS: Mathematics, Discrete Mathematics and Combinatorics, Geometry and Topology, bilinear form, Representation Theory (math.RT), Quadratic and bilinear forms, inner products, Mathematics - Representation Theory
tetrahedron Lie algebra, Numerical Analysis, 05E30,15A21, Eigenvalues, singular values, and eigenvectors, Algebra and Number Theory, Canonical forms, reductions, classification, tridiagonal pair, eigenvalues, Mathematics - Rings and Algebras, Tetrahedron Lie algebra, 33C45, Tridiagonal pair, 33C45; 05E30,15A21, Krawtchouk type tridiagonal pair, Rings and Algebras (math.RA), Leonard pair, FOS: Mathematics, Discrete Mathematics and Combinatorics, Geometry and Topology, bilinear form, Representation Theory (math.RT), Quadratic and bilinear forms, inner products, Mathematics - Representation Theory
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