Pairs of commuting isometries, I
We present an explicit version of Berger, Coburn and Lebow’s classification result for pure pairs of commuting isometries in the sense of an explicit recipe for constructing pairs of commuting isometric multipliers with precise coefficients. We describe a complete set of (joint) unitary invariants and compare Berger, Coburn and Lebow’s representations with other natural analytic representations of pure pairs of commuting isometries. Finally, we study the defect operators of pairs of commuting isometries.
Maji, Amit; Sarkar, Jaydeb; and Sankar, T. R., "Pairs of commuting isometries, I" (2019). Journal Articles. 1037.