Extended Horn clauses: the framework and some semantics

Abstract

The purpoee of this paper is twofold: to introduce a new extension of concurrent logic programming languages aiming at handling synchronicity and to present and compare several semantics for it. The extended framework -ntially rests on an extension of Horn clauses, including multiple atoms in their head.a and a guard construct, u well u. a new operator between goals. The semantics discUlllled conaiat of four semantics. They range in the operational, declarative and denotational types and are issued both from the logic programming tradition and the imperative tradition. They are compos8d of an operational semantics, describing the ( claasical) success set a.nd failure set, of two declarative semantics, extending the Herbrand interpretation and the immediate consequence operator to the extended framework, and of a denotational semantics, defined compositionally and on the basis of histories pouibly involving hypothetical statements. The mathematical tools mainly used are complete lattices a.nd complete metric spaces.

Extending the μLog Framework with Local and Conditional Blackboard Operations

“…Other languages similar to µLog include Gamma (Banatre and Le Métayer, 1993), LO (Andreoli and Pareschi, 1991), Communicating Clauses (Jacquet and Monteiro, 1992), and the mechanism proposed in Brogi (1990). All of them transform in one way or another a multiset of elements into another one.…”

A coordination language for collective agent based systems

“…GroupLog defines extensions to the Extended Horn Clause language (EHC) [29], that are supported at two levels: L1, defines agents as program units and L2 defines groups of agents. A GroupLog system contains concurrently executing agents able to: (1) communicate through interface predicates, and (2) join groups to coordinate their activities.…”

“…A GroupLog system contains concurrently executing agents able to: (1) communicate through interface predicates, and (2) join groups to coordinate their activities. In the following, we first summarize EHC (see [29]), and then describe the two mentioned levels.…”