The ϑ-lower and T-upper fuzzy rough approximation operators on a semigroup

In this paper, we consider a semigroup as a universal set and investigate the properties of ϑ-lower and T-upper fuzzy rough approximation operators. A new fuzzy algebraic structure, called a TL-fuzzy rough semigroup, is introduced and some related properties are studied. Finally, the homomorphism properties of ϑ-lower and T-upper fuzzy rough approximation operators are investigated.