Inverse spectral problems for integro-differential operators address the challenge of reconstructing the underlying operator – often comprising both differential and integral components – from its ...

The spectrum of the canonical operator in the noncommutative 2-torus Tθ depending on the parameter θ ∈ [0,1] © Douglas Hofstadter's butterfly. Licensed under ...

Let T = H + iK be hyponormal and 𝜑 be a strictly monotone increasing continuous function on σ(H). We define $\tilde{\varphi}(T)$ by $\tilde{\varphi}(T)=\varphi (H)+iK$. In this paper, we show that if ...

Spectral problems in boundary value problems constitute a fundamental area of applied mathematics and mathematical physics, where the focus lies on determining eigenvalues and corresponding ...