Showing 2025 · math.FAShow all
3 papers · 2 filters
math.FA2025
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…
math.FA2025
Invariant subspaces of Brownian shifts on vector-valued Hardy spaces
Nilanjan Das, Soma Das, Jaydeb Sarkar
We characterize invariant subspaces of Brownian shifts on vector-valued Hardy spaces. We also solve the unitary equivalence problem for the invariant subspaces of these shifts.
math.FA2025
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…