Unitary invariants in multivariable operator theory
  The problems considered in this paper come as a natural continuation of our program to develop a free analogue of Sz.-Nagy-Foias theory, for row contractions. The paper is structured as follows:   Introduction   Part I. Unitary invariants for n-tuples of operators   1. Joint numerical radius   2. Euclidean operator radius   3. Joint numerical range and spectrum   4. $\rho$-operator radius   Part II. Joint operator radii, inequalities, and applications   5. von Neumann inequalities   6. Constrained von Neumann inequalities   7. Multivariable Haagerup-de la Harpe inequalities   8. Multivariable Fejer inequalities   References 
Gelu Popescu