Semigroup properties of linear terms

Abstract

The concept of linear terms of a given type [Formula: see text] (terms in which each variable occurs at most once) was introduced by M. Couceiro and E. Lethonen in [Galois theory for sets of operations closed under permutation, cylindrification and composition, Algebr. Univ. 67 (2012) 273–297, doi:10.1007/s00012-012-0184-1] (see also [T. Changphas, K. Denecke and B. Pibaljommee, Linear terms and linear hypersubstitutions, SEAMS Bull. Math. 40 (2016) (to be published).]). In this paper, we introduce binary partial operations [Formula: see text] and [Formula: see text] on the set [Formula: see text] of all linear terms of type [Formula: see text] Then we characterize regular elements and Green’s relations in these partial algebras.