Document Type : Research Paper


Department of Mathematics, Hakim Sabzevari University, P.O. Box 397, Sabzevar, Iran.


We offer a new definition of $\varepsilon$-orthogonality in normed spaces, and we try to explain some properties of which. Also we introduce some types of $\varepsilon$-orthogonality in an arbitrary  $C^\ast$-algebra $\mathcal{A}$, as a Hilbert $C^\ast$-module over itself, and investigate some of its properties in such spaces. We state some results relating range-kernel orthogonality in $C^*$-algebras.


Main Subjects

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