Revealed preference theory was initiated by Samuelson [8] as a way of defining the rational behaviour of a consumer in terms of a preference relation associated with a demand function. This topic has been axiomatically treated by Arrow (1959), Richter (1966), Sen (1971) and many others. Papers Banerjee (1995), Georgescu (2004; 2005) attempt at developing a theory of revealed preference for fuzz...

The first part of this paper provides a comprehensive and self-contained account of the interrelationships between algebraic properties of varieties and properties of their free algebras and equational consequence relations. In particular, proofs are given of known equivalences between the amalgamation property and the Robinson property, the congruence extension property and the extension prope...

The plactic monoid is the quotient of the free monoid by the congruence generated by Knuth’s well-celebrated rules. It is well-known that the set of Young tableaux is a cross-section of this congruence which happens to be regular. The main result of this work shows that the set of alphabetically minimal elements in the congruence classes is also regular. We give a full combinatorial characteriz...

We show that theories presented by a set of ground equations with several associative-commutative (AC) symbols always admit a nite canonical system. This result is obtained through the construction of a reduction ordering which is AC-compatible and total on the set of congruence classes generated by the associativity and commutativity axioms. As far as we know, this is the rst ordering with suc...

The study of structure systems, an abstraction of the concept of firstorder structures, is continued. Structure systems have algebraic systems rather than universal algebras as their algebraic reducts. Moreover, their relational component consists of a collection of relation systems on the underlying functors rather than simply a system of relations on a single set. Congruence systems of struct...

The variety (equational class) of lambda abstraction algebras was introduced to algebraize the untyped lambda calculus in the same way cylindric and polyadic algebras algebraize the first-order predicate logic. In this paper we prove that the lattice of lambda theories is not modular and that the variety generated by the term algebra of a semi-sensible lambda theory is not congruence modular. A...

Abstract Fuzzy set (FS) theory and rough sets (RSs) are constructed to accommodate the data uncertainty. In contrast, bipolar FS (BFS) can tackle uncertainty bipolarity of in different circumstances. This article aims introduce idea fuzzy ideals semigroup (SG), which is a generalization concept BFSs (RBFSs) an SG. We also investigate roughness subsemigroup (BF-SSG) with help congruence relation...

Congruence among the Intended, Implemented and Attained “Thinking and Life Style” Curricula in the Eighth Grade M. A. Jamalifar Sh. Hashemi Moghadam, Ph.D. Z. Abedi Karajiban, Ph.D. A.R. Faghihi, Ph.D. The present study was carried out to examine the congruence among the intended, implemented and attained “thinking and life style” curricula in th...