The aim of this paper is to work with the measure of nonhyperconvexity in a similar way as J. Cano (1990) does with the index of nonconvexity. We apply this measure to obtain different extensions of the famous Schauder fixed-point theorem in hyperconvex spaces.
"Measure of nonhyperconvexity and fixed-point theorems." Abstr. Appl. Anal. 2003 (2) 111 - 119, 30 January 2003. https://doi.org/10.1155/S1085337503205017