Volume 16, 1997, No. 4


A Semantic Base for the Fuzzy Extension-Principle

H. Becker

Abstract. A distance/semantic is attached to fuzzy acceptabilities. Within the frame of this semantic, a modified version of the extension principle proves to be obligatory. It is derived without referring to fuzzy logic and coincides only  under certain assumptions with the usual version of the extension principle. Over that, it is shown under not very restricting assumptions that membership-functions which are compatible with the above semantic have to be automatically of that triangle- or trapezoid type which is so popular in fuzzy applications.

 

On the Automatic Synthesis of Social Laws for Mobile Robots. A Study in Artificial Social Systems

O. Ben-Yitzhak, M. Tennenholtz

Abstract. We introduce an algorithm for the automatic synthesis of social laws for mobile robots. Our algorithm generates useful social laws for any 2/connected grid-like environment with arbitrary obstacles. We prove that the social laws generated by our algorithm enable the agents to achieve their goals while preventing collisions. Moreover, computer simulations show that the social laws generated by the algorithm lead to efficient behaviour in a large set of environments. Our work bridges the gap between the work on the automatic synthesis of social laws in abstract models, and work on hand-crafting social laws for a particular domain.

 

A Prolog Technique of Implementing Search of A/O Graphs with Constraints

M. Bieliková, P. Návrat

Abstract. Our research has been motivated by the task of forming a solution subgraph which satisifies given constraints. The problem is represented by an A/O graph. Our approach is to apply a suitably modified technique of dependency-directed backtracking. We present our formulation of the standard chronological backtracking algorithm in Prolog. Based on it, we have developed an enhanced algorithm which makes use of special heuristic knowledge. It involves also the technique of node marking. We have gathered experience with the prototype Prolog implementation of the algorithm in applying it to (one step of) the problem of building a software configuration. Our experience shows that Prolog programming techniques offer a considerable flexibility in implementing the above outlined tasks.

 

Blackboard- and Object-Based Systems via Multi-Head Clauses

A. Ciampolini, El Lamma, C.Stefanelli, P. Mello

Abstract. This paper presents a distributed architecture supporting and integrating both blackboard- and object-based multi-agent models. The architecture is based on a concurrent logic language with multi-head clauses, committed/choice behaviour and restricted AND parallelism. A blackboard/based application is mapped into a set of multi-head clauses representing logic agents which communicate via a common (possibly distributed) working memory. Objects are clusters of processes, objects' state is represented by logical variables, message-passing communication between objects is performed via multi-head clauses and inheritance is obtained as union of clauses. Thanks to the parallel nature of the underlying concurrent language, we obtain a distributed implementation where parallelism is highly exploited.

  

Embedding Rings into Faulty Twisted Hypercubes

E. Abuelrub, S. Bettayeb

Abstract. The hypercube is emerging as one of the most effective and popular network architectures for large scale parallel machines. Hypercube based machines are becoming more popular due to many of their attractive features in parallel computing. An attractive version of the hypercube is the twisted hypercube. It preserves many properties of the hypercube and most importantly reduces the diameter by a factor of two. In this paper we present optimal embeddings of rings into faulty twisted hypercubes with up to 2n-3 faulty processes.


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