9 papers
Invariant subspaces of Jordan blocks of
Sneha B, Jaydeb Sarkar, Michio Seto
It is known that invariant subspaces of classical Jordan blocks of the Hardy space over the open unit disc are described by factorizations of inner functions. In the polydisc setti…
Hyponormal contractions and analytic shifts
Sneha B, Neeru Bala, Jaydeb Sarkar
Hyponormal operators are known to be among the most difficult operators to analyze. In this work, we focus on two finite types of hyponormal operators. The first type becomes analy…
Foguel-type operators similar to contractions
Nilanjan Das, Soma Das, Jaydeb Sarkar
Pisier's celebrated counterexample to Halmos's similarity-to-contractions problem was based on upper triangular block operator matrices involving three classical opera…
Paired and Toeplitz + Hankel operators
Nilanjan Das, Soma Das, Jaydeb Sarkar
We present complete classifications of Toeplitz + Hankel operators on vector-valued Hardy spaces and classify paired operators on . We also study the latter class…
New norm estimate for composition operators
Preeti Kumari, P. Muthukumar, Jaydeb Sarkar
The classical Littlewood's theorem establishes boundedness and provides a norm estimate for composition operators on the Hardy space. In this paper, we offer an alternative proof o…
Finite-dimensional model spaces invariant under composition operators
P. Muthukumar, Jaydeb Sarkar, Batzorig Undrakh
Finite-dimensional model spaces are quotient spaces of the Hardy space on the open unit disc, determined by finite Blaschke products. Composition operators, on the other hand, act…