Dual of Alsina equation A. Sai Hareesh and Prabhakar Akella * Department of Mathematics and Computer Science, Sri Sathya Sai University, Prasanthi Nilayam - 515 134, India Abstract In this paper we deal with the functional equation T (S (x, y),S (x, N (y))) = x where T is a t-norm, S is a t-conorm and N is a strong negation. This equation is the dual of the functional equation solved by Alsina. We give a complete characterization of continuous t-norms and con- tinuous t-conorms which satisfy the given equation. Keywords: t-norms, t-conorms, strong negation, Alsina equation. 1 Introduction The study of functional equations involving fuzzy logic based operators is of long standing and rich in content. The functional equations which are studied are generalizations of equations involving crisp set theoritic operations. An account of the study of some such equations can be found in [2]. One such equation in literature is the Alsina equation which is the generalization of the set theoritic equation A = (A ∪ B) ∩ (A ∪ B c ). The functional equation of Alsina involving a t-norm and a t-conorm is: S (T (x, y),T (x, N (y))) = x, (1) * akella.prabhakar@gmail.com 1