Measures of noncompactness in Hilbert $C^{\ast }$-modules

Dragoljub J. Kečkić, Zlatko Lazović

Consider a countably generated Hilbert $C^{\ast }$-module $\mathcal{M}$ over a $C^{\ast }$-algebra $\mathcal{A}$. There is a measure of noncompactness $\lambda$ defined, roughly as the distance from f…