4 papers
Cayley--Hamilton tuples: an interplay between algebraic varieties and joint spectra
B. Krishna Das, Poornendu Kumar, Haripada Sau
We introduce the notion of Cayley--Hamilton tuples: these are commuting operator tuples that are annihilated by a non-zero polynomial and such that its Taylor joint spectrum coinci…
Zeros of Holomorphic Functions in Commuting and Non-commuting Variables as Spectral Data
Poornendu Kumar, Jeet Sampat
We characterize the zero sets of functions in the Schur--Agler class over the unit polydisk as well as functions in the unit ball of the multiplier algebra of the Drury--Arveson sp…
Annihilating ideals and Agler--McCarthy spectral varieties in the bidisc
Raphaël Clouâtre, Poornendu Kumar
The closed unit bidisc is known to be a spectral set for any pair of commuting contractions. When each is pure and has finite defect, th…
Distinguished varieties and the Nevanlinna-Pick interpolation problem on the symmetrized bidisk
B. Krishna Das, Poornendu Kumar, Haripada Sau
Starting with a solvable Nevanlinna-Pick interpolation problem with the initial data coming from the symmetrized bidisk, this paper studies the corresponding uniqueness set, i.e.,…