Gram matrices and Stirling numbers of a class of diagram algebras, II

Abstract

In the paper [6], we introduced Gram matrices for the signed partition algebras, the algebra of Z₂-relations and the partition algebras. (s₁, s₂, r₁, r₂, p₁, p₂)-Stirling numbers of the second kind are also introduced and their identities are established. In this paper, we prove that the Gram matrix is similar to a matrix which is a direct sum of block submatrices. As a consequence, the semisimplicity of a signed partition algebra is established.