T-roughness in semigroups
Qimei Xiao · 2011
In this paper, we introduce the concept of (strong) set-valued homomorphism of a lattice which is a generalization of ordinary lattice homomorphism. We constructed generalized lower and upper approximation operators, by means of a set-valued mapping, which is a generalization of the notion of lower and upper approximations of a lattice, and related properties are investigated.