English

Multiplicative and Jordan multiplicative maps on structural matrix algebras

Rings and Algebras 2025-11-26 v2

Abstract

Let MnM_n denote the algebra of n×nn \times n complex matrices and let AMn\mathcal{A}\subseteq M_n be an arbitrary structural matrix algebra, i.e. a subalgebra of MnM_n that contains all diagonal matrices. We consider injective maps ϕ:AMn\phi : \mathcal{A}\to M_n that satisfy the condition ϕ(XY)=ϕ(X)ϕ(Y),for all X,YA, \phi(X \bullet Y) = \phi(X) \bullet \phi(Y), \quad \text{for all } X,Y \in \mathcal{A}, where \bullet is either the standard matrix multiplication (X,Y)XY(X,Y)\mapsto XY, the Jordan product (X,Y)XY+YX(X,Y) \mapsto XY+YX, or the normalized Jordan product (X,Y)12(XY+YX)(X,Y) \mapsto \frac{1}{2}(XY+YX). We show that all such maps ϕ\phi are automatically additive if and only if A\mathcal{A} does not contain a central rank-one idempotent. Moreover, in this case, we fully characterize the form of these maps.

Keywords

Cite

@article{arxiv.2503.14116,
  title  = {Multiplicative and Jordan multiplicative maps on structural matrix algebras},
  author = {Ilja Gogić and Mateo Tomašević},
  journal= {arXiv preprint arXiv:2503.14116},
  year   = {2025}
}

Comments

16 pages, to appear in Linear Multilinear Algebra

R2 v1 2026-06-28T22:25:03.353Z