2024 : 9 : 16
Davood Alimohammadi

Davood Alimohammadi

Academic rank: Associate Professor
ORCID: https://orcid.org/0000-0002-9398-6213
Education: PhD.
ScopusId: 6505995626
HIndex:
Faculty: Science
Address: Arak University
Phone:

Research

Title
Surjective norm-additive maps between‎ ‎$ C(X,\tau)$-algebras
Type
Presentation
Keywords
,R+-homogeneous map‎, ‎Norm-additive in modulus map‎, ‎Topological involution‎ Uniform algebra.d
Year
2024
Researchers Davood Alimohammadi

Abstract

‎In this paper‎, ‎we study surjective $\mathbb{R}^+$-homogeneous‎ ‎norm-additive in modulus between $ C(X‎, ‎\tau)$-algebras‎. ‎We first show‎ ‎that if $ X $ and $ Y $ are compact Hausdorff spaces‎, ‎$ \tau $ and $ \eta $‎ ‎are topological involutions on $ X $ and $ Y $‎, ‎respectively‎, ‎and‎ ‎$ T‎: ‎C(X,\tau) \longrightarrow C(Y‎, ‎\eta) $ is a surjective $\mathbb{R}^+$-homogeneous‎ ‎norm-additive in modulus‎, ‎then there exists a unique bijective map‎ ‎$ \Phi‎ : ‎Y_{\eta} \longrightarrow X_{\tau} $ such that‎ ‎$ |T(f)(y)| = |f(x)| $ for all $ f \in C(X‎, ‎\tau)$‎, ‎$y \in Y $‎ ‎and $ x \in \Phi(y_{\eta}) $‎, ‎where $ x_{\tau} = \{x‎, ‎\,\,\tau(x)\} $‎ ‎for all $ x \in X $‎, ‎$ X_{\tau} = \{ x_{\tau}:\,\‎, ‎x \in X \} $‎, ‎$ y_{\eta} = \{ y,\,\‎, ‎\eta(y)\} $‎ ‎for all $ y \in Y $ and $ Y_{\eta} = \{ y_{\eta}:\,\‎, ‎y \in Y \} $‎. ‎We next show that if $ T‎: ‎C_{\mathbb{R}}(X) \longrightarrow C_{\mathbb{R}}(Y)$‎ ‎is a surjective $\mathbb{R}^+$-homogeneous‎ ‎norm-additive in modulus‎, ‎then there exists a homeomorphism‎ ‎$ \varphi‎ : ‎Y \longrightarrow X $ such that‎ ‎$ |T(f)(y)| = |f(\varphi(y))| $ for all $ f \in C(X,\tau) $‎ ‎and $ y \in Y $‎, ‎where $ X $ and $ Y $ are compact Hausdorff spaces‎.d