Noncommutative BKW-Operators

Fuente: arXiv
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Autores principales: S., Arunkumar C., Sruthymurali
Formato: Preprint
Publicado: 2025
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author S., Arunkumar C.
Sruthymurali
author_facet S., Arunkumar C.
Sruthymurali
contents Inspired by the classical Bohman-Korovkin-Wulbert (BKW) operators, we initiate a study of noncommutative BKW-operators. Let $A$ be a unital $C^*$-algebra, and $S$ be a set of generators of $A$. A unital completely positive (UCP)-map $ϕ: A\rightarrow B(H)$ is said to be a \textit{noncommutative BKW-operator} for $S$ with respect to norm or weak operator topology (WOT) or strong operator topology (SOT) if for any sequence of UCP-maps $ϕ_n:A\rightarrow B(H)$, $n=1,2,...,$ $\lim_{n\rightarrow \infty}ϕ_n(s)=ϕ(s),\forall ~s\in S$ in norm (or WOT or SOT) $\Rightarrow \lim_{n\rightarrow \infty}ϕ_n(a)=ϕ(a), \forall ~a\in A$ in norm (or WOT or SOT, respectively). We identify a connection between noncommutative BKW-operators and the unique CP-extension of UCP-maps. We have discussed several examples and explored different notions of noncommutative BKW-operators and their interconnections. Additionally, we introduce the concept of hyperrigidity with respect to a UCP-map and characterize it along the lines of Arveson. Although independent yet related to noncommutative BKW-operators, we provide a noncommutative version of operator version of the Korovkin theorem recently proposed by D. Popa.
format Preprint
id arxiv_https___arxiv_org_abs_2510_24470
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Noncommutative BKW-Operators
S., Arunkumar C.
Sruthymurali
Operator Algebras
Functional Analysis
41A36, 46L05
Inspired by the classical Bohman-Korovkin-Wulbert (BKW) operators, we initiate a study of noncommutative BKW-operators. Let $A$ be a unital $C^*$-algebra, and $S$ be a set of generators of $A$. A unital completely positive (UCP)-map $ϕ: A\rightarrow B(H)$ is said to be a \textit{noncommutative BKW-operator} for $S$ with respect to norm or weak operator topology (WOT) or strong operator topology (SOT) if for any sequence of UCP-maps $ϕ_n:A\rightarrow B(H)$, $n=1,2,...,$ $\lim_{n\rightarrow \infty}ϕ_n(s)=ϕ(s),\forall ~s\in S$ in norm (or WOT or SOT) $\Rightarrow \lim_{n\rightarrow \infty}ϕ_n(a)=ϕ(a), \forall ~a\in A$ in norm (or WOT or SOT, respectively). We identify a connection between noncommutative BKW-operators and the unique CP-extension of UCP-maps. We have discussed several examples and explored different notions of noncommutative BKW-operators and their interconnections. Additionally, we introduce the concept of hyperrigidity with respect to a UCP-map and characterize it along the lines of Arveson. Although independent yet related to noncommutative BKW-operators, we provide a noncommutative version of operator version of the Korovkin theorem recently proposed by D. Popa.
title Noncommutative BKW-Operators
topic Operator Algebras
Functional Analysis
41A36, 46L05
url https://arxiv.org/abs/2510.24470