Triangular Scheme Revisited in the Light of n-permutable Categories

Abstract

The first diagrammatic scheme was developed by H.P. Gumm under the name Shifting Lemma in case to characterize congruence modularity. A diagrammatic scheme is developed for the generalized semi distributive law in Mal'tsev categories. In this paper we study this diagrammatic scheme in the context of $n$-permutable, and of Mal'tsev categories in particular. Several remarks concerning the Triangular scheme case are included.