Characterizations of the semi-harmonious and harmonious quasi-projection pairs on Hilbert $C^{\ast }$-modules

Xiaoyi Tian, Qingxiang Xu, Chunhong Fu

For each adjointable idempotent $Q$ on a Hilbert $C^{\ast }$-module $H$, a specific projection $m(Q)$ called the matched projection of $Q$ was introduced recently due to the characteriza…