Orthogonally Additive Mappings on Hilbert Modules

Abstract

In this paper, we study the representation of orthogonally additive mappings acting on Hilbert $C^{\ast }$-modules and Hilbert $H^{\ast }$-modules. One of our main results shows that every continuous orthogonally additive mapping $f$ from a Hilbert module $W$ over $\K(\H)$ or $\stackrel{˝}{\S }(\stackrel{˝}{)}$ to a complex normed space is of the form $f(x)=T(x)+\Phi (<x,x>)$ for all $x\in W$, where $T$ is a continuous additive mapping, and $\Phi$ is a continuous linear mapping.

22 pages