On the equational de$nition of the least pre$xed point
نویسنده
چکیده
We propose a method to axiomatize by equations the least pre$xed point of an order preserving function. We discuss its domain of application and show that the Boolean modal -calculus has a complete equational axiomatization. The method relies on the existence of a “closed structure” and its relationship to the equational axiomatization of Action Logic is made explicit. The implication operation of a closed structure is not monotonic in one of its variables; we show that the existence of such a term that does not preserve the order is an essential condition for de$ning by equations the least pre$xed point. We stress the interplay between closed structures and $xed point operators by showing that the theory of Boolean modal -algebras is not a conservative extension of the theory of modal -algebras. The latter is shown to lack the $nite model property. c © 2002 Elsevier Science B.V. All rights reserved.
منابع مشابه
APPROXIMATE FIXED POINT IN FUZZY NORMED SPACES FOR NONLINEAR MAPS
We de ne approximate xed point in fuzzy norm spaces and prove the existence theorems, we also consider approximate pair constructive map- ping and show its relation with approximate fuzzy xed point.
متن کاملON COMPACTNESS AND G-COMPLETENESS IN FUZZY METRIC SPACES
In [Fuzzy Sets and Systems 27 (1988) 385-389], M. Grabiec in- troduced a notion of completeness for fuzzy metric spaces (in the sense of Kramosil and Michalek) that successfully used to obtain a fuzzy version of Ba- nachs contraction principle. According to the classical case, one can expect that a compact fuzzy metric space be complete in Grabiecs sense. We show here that this is not the case,...
متن کاملProperties of Fixed Points in Axiomatic Domain Theory
Fixed points play a central role in domain theory, where, traditionally, the least-xed-point operator for continuous endofunctions on complete partial orders (cpos) is used. Recently, there has been considerable interest in developing a more general axiomatic (and order-free) account of the constructions of domain theory. Peter Freyd made an essential contribution to this programme by emphasisi...
متن کاملA Fixed Point Theorem in Probabilistic Metric Spaces with a Convex Structure
The inequality Ffx;fy(qs) Fx;y(s) (s 0), where q 2 (0; 1), is generalized for multivalued mappings in many directions. Using Hausdor distance S.B. Nadler in [7] introduced a generalization of Banach contraction principle in metric spaces. In [3] the de nition of probabilistic Nadler q-contraction is given. Using some results given in [12] a xed point theorem on spaces with a convex structure is...
متن کاملDually quasi-De Morgan Stone semi-Heyting algebras II. Regularity
This paper is the second of a two part series. In this Part, we prove, using the description of simples obtained in Part I, that the variety $mathbf{RDQDStSH_1}$ of regular dually quasi-De Morgan Stone semi-Heyting algebras of level 1 is the join of the variety generated by the twenty 3-element $mathbf{RDQDStSH_1}$-chains and the variety of dually quasi-De Morgan Boolean semi-Heyting algebras--...
متن کامل