A new generalization of Calbrix–Troallicʼs theorem

The paper introduces new concepts of lower pseudo-quasicontinuity and lower covering categorical cliquishness for multi-value maps and use them to set a general theorem on the points of jointly continuity of mappings f : X × Y → Z , yielding as a partial case a previous result of the authors [9] as well as a result of A. Bouziad and J.P. Troallic [10].