(φ,ψ)-derivations of BL-algebras
Abstract
In this paper, the notions of derivations of types 1 and 2 on a BL-algebraL are introduced. We extend the notions of these derivations by introducing the notions of (φ,ψ)-derivations of types 1 and 2, and discuss some related properties. The conditions for (φ,ψ)-derivations of types 1 and 2 to be isotone are provided. The set FixD(L) is defined and conditions for FixD(L) to be a down closed set and an ideal on L are given where L is a Boolean algebra and D is a (φ,ψ)-derivation of type 1 on L. Finally, the relationship between φ-derivations of types 1 and 2 for a Boolean algebra L is determined.
Communicated by P. Corsini