Triangular norms as ordinal sums of semigroups in the sense of A. H. Clifford

Abstract

Ordinal sums of semigroups in the sense of [3] leading to triangular norms [29] are studied, generalizing the ordinal sum of triangular norms [30]. The summands of these general ordinal sums are fully characterized, and the ordinal irreducibility of triangular norms is investigated, inducing a natural partition of the class of all triangular norms.