Yuanqi Sang

activity

20162026

collaborators

7 papers

math.FA2026

Examples of Noncompact Quasinilpotent Hankel Operators

Yuanqi Sang

For every nonzero real number $a,$ we prove that the integral Hankel operator on $L^{2} (R_{+})$ with kernel $k (t) = t^{- 1 + ia}$ is noncompact quasinilpotent. This answers in the…

math.FA2026

The Cesàro Operator is in the Toeplitz Algebra

Yuanqi Sang

Let $T$ denote the $C^{*}$ -algebra generated by all bounded Toeplitz operators on the Hardy space of the unit disk. Barr\'ıa and Halmos [\emph{Trans. Amer. Math. Soc.} \textb…

math.FA2026

A Characterization of Complex Symmetric Weighted Composition Operators on the Fock Space

Yuanqi Sang, Liankuo Zhao

We characterize all bounded complex symmetric weighted composition operators on the Fock space $\mathcal F_α^{2}$, without prescribing a conjugation a priori. Our approach uses r…

math.FA2026

Brown-Halmos type theorems for generalized Cauchy singular integral operators and applications

Yuanqi Sang, Liankuo Zhao

We investigate the commutativity and semi-commutativity of generalized singular integral operators of the form $P_{+} f P_{+} + P_{-} g P_{+} + P_{+} u P_{-} + P_{-} v P_{-}$ on $L…

math.FA2022

Algebras of Generalized Singular Integral Operators with Cauchy kernel

Yuanqi Sang

For bounded Lebesgue measurable functions $f, g, ϕ$ and $ψ$ on the unit circle, $P_{+} f P_{+} + P_{-} g P_{+} + P_{+} ϕ P_{-} + P_{-} ψ P_{-}$ is called a generalized singular integral operator…

math.FA2020

Projections in Toeplitz algebra

Hui Dan, Xuanhao Ding, Kunyu Guo +1

Motivated by Barr{\'ı}a-Halmos's \cite[Question 19]{barria1982asymptotic} and Halmos's \cite[Problem 237]{Halmos1978A}, we explore projections in Toeplitz algebra on the Hardy spac…

math.FA2016

The pluriharmonic Hardy space and Toeplitz Operators

Yuanqi Sang, Xuanhao Ding

Compared with harmonic Bergman spaces, this paper introduces a new function space which is called the pluriharmonic Hardy space $h^{2} (T^{2})$ . We character (semi-) commut…