Generalized arithmetic operators and their relationship to t-norms in interval-valued fuzzy set theory

In this paper we study extensions of the arithmetic operators +, −, ·, ÷ to the lattice L of closed subintervals of the unit interval. Starting from a minimal set of axioms that these operators must fulfill, we investigate which properties they satisfy. We also investigate some classes of t-norms on L which can be generated using these operators; these classes provide natural extensions of the Lukasiewicz, product, Frank, Schweizer–Sklar and Yager t-norms to L .