English

New insights into linear maps which are anti-derivable at zero

Operator Algebras 2025-12-11 v1

Abstract

Let AA be a Banach algebra admitting a bounded approximate unit and satisfying property B\mathbb{B}. Suppose T:AXT: A \rightarrow X is a continuous linear map, where XX is an essential Banach AA-bimodule. We prove that the following statements are equivalent: (i)(i) TT is anti-derivable at zero (i.e., ab=0a b =0 in AA T(b)a+bT(a)=0\Rightarrow T(b)\cdot a + b\cdot T(a) =0); (ii)(ii) There exist an element ξX\xi \in X^{**} and a linear map (actually a bounded Jordan derivation) d:AXd: A\to X satisfying ξa=aξX\xi \cdot a = a \cdot \xi \in X, T(a)=d(a)+ξaT(a) = d(a) +\xi \cdot a, and d(b)a+bd(a)=2ξ(ba),d(b)\cdot a + b\cdot d(a)= - 2 \xi \cdot (b a), for all a,bAa,b\in A with ab=0a b =0. Assuming that AA is a C^*-algebra we show that a bounded linear mapping T:AXT: A\to X is anti-derivable at zero if, and only if, there exist an element ηX\eta \in X^{**} and an anti-derivation d:AXd: A \rightarrow X satisfying ηa=aηX\eta \cdot a = a \cdot \eta \in X, η[a,b]=0\eta \cdot [a,b] = 0 {\rm(}i.e., Lη:AAL_{\eta}: A \to A, Lη(a)=ηaL_{\eta} (a) = \eta \cdot a vanishes on commutators{\rm)}, and T(a)=d(a)+ηaT(a) = d(a) +\eta \cdot a, for all a,bAa,b \in A. The results are also applied for some special operator algebras.

Keywords

Cite

@article{arxiv.2512.09578,
  title  = {New insights into linear maps which are anti-derivable at zero},
  author = {Jiankui Li and Antonio M. Peralta and Shanshan Su},
  journal= {arXiv preprint arXiv:2512.09578},
  year   = {2025}
}
R2 v1 2026-07-01T08:18:44.538Z