Wold decompositions for representations of C∗-algebras associated with noncommutative varieties

Abstract

Given a set Q of polynomials in noncommutative indeterminates Z1,…,Zn and a regular domain Dmp(H)⊂B(H)n, m,n∈N, associated with a positive regular polynomial p∈C⟨Z1,…,Zn⟩, we consider the variety VQ(H):={X=(X1,…,Xn)∈Dmp(H):g(X)=0 for all g∈Q}. Each variety VQ(H) admits a {\it universal model} B=(B1,…,Bn). The main goal of the paper is to study the structure of the ∗-representations of the C∗-algebra C∗(VQ) generated by B1,…,Bn and the identity.