English

Orthogonality-preserving, C*-conformal and conformal module mappings on Hilbert C*-modules

Operator Algebras 2025-04-29 v3 Functional Analysis

Abstract

We investigate orthonormality-preserving, C*-conformal and conformal module mappings on Hilbert C*-modules to obtain their general structure. Orthogonality-preserving bounded module maps T act as a multiplication by an element \lambda of the center of the multiplier algebra of the C*-algebra of coefficients combined with an isometric module operator as long as some polar decomposition conditions for the specific element \lambda are fulfilled inside that multiplier algebra. Generally, T always fulfils the equality <T(x),T(y)>=λ2<x,y><T(x),T(y) > = | \lambda |^2 < x,y> for any elements x,y of the Hilbert C*-module. At the contrary, C*-conformal and conformal bounded C*-linear mappings are shown to be only the positive real multiples of isometric module operators.

Keywords

Cite

@article{arxiv.0907.2983,
  title  = {Orthogonality-preserving, C*-conformal and conformal module mappings on Hilbert C*-modules},
  author = {Michael Frank and Alexander S. Mishchenko and Alexander A. Pavlov},
  journal= {arXiv preprint arXiv:0907.2983},
  year   = {2025}
}

Comments

13 pages / Thm. 1.3, second paragraph of proof - corrected, minor changes of formulations in the text, references updated

R2 v1 2026-06-21T13:25:58.356Z