Essential representations of C*-correspondences

Finitely Correlated Representations of Product Systems of $C^*$-Correspondences over $\mathbb{N}^k$

We study isometric representations of product systems of correspondences over the semigroup $\mathbb{N}^k$ which are minimal dilations of finite dimensional, fully coisometric representations. We show the existence of a unique minimal cyclic coinvariant subspace for all such representations. The compression of the representation to this subspace is shown to be complete unitary invariant. For a certain class of graph algebras the nonself-adjoint \textsc{wot}-closed algebra generated by these representations is shown to contain the projection onto the minimal cyclic coinvariant subspace. This cl…

Unit Vectors, Morita Equivalence and Endomorphisms

We solve two problems in the theory of correspondences that have important implications in the theory of product systems. The first problem is the question whether every correspondence is the correspondence associated (by the representation theory) with a unital endomorphism of the algebra of all adjointable operators on a Hilbert module. The second problem is the question whether every correspondence allows for a nondegenerate faithful representation on a Hilbert space. We also resolve an extension problem for representations of correspondences and we provide new efficient proofs of several w…

Toeplitz Algebras of Correspondences and Endomorphisms of Sums of Type I Factors

It is a well-known fact that endomorphisms of $B(H)$ are intimately connected with families of mutually orthogonal isometries, i.e. with representations of the so-called Toeplitz $C^*$-algebras. In this paper we consider a natural generalization of this connection between the representation theory of certain $C^*$-algebras associated to graphs and endomorphisms of certain von Neumann subalgebras of $B(H)$. Our primary results give criteria by which it may be determined if two representations give rise to equal or conjugate endomorphisms.

Quantum Markov Processes (Correspondences and Dilations)

We study the structure of quantum Markov Processes from the point of view of product systems and their representations.

对应表示的极大性

Maximality of correspondence representations

本文完全刻画了C*-对应的极大表示，强化了先前结果，并通过多种例子展示判据，描述非交换Choquet边界，为Arveson超刚性猜想提供更多反例。

Doubly commuting invariant subspaces for representations of product systems of $C^*$-correspondences

We obtain a Shimorin-Wold-type decomposition for a doubly commuting covariant representation of a product system of $C^*$-correspondences. This extends a recent Wold-type decomposition by Jeu and Pinto for a $q$-doubly commuting isometries. Application to the wandering subspaces of doubly commuting induced representations is explored, and a version of Mandrekar's Beurling type theorem is obtained to study doubly commuting invariant subspaces using Fock space approach due to Popescu.