Distributed First Order Logic

Distributed First Order Logic (DFOL) is a formalism introduced more than 10 years ago with the purpose of formalising distributed knowledge-based systems. In these systems, knowledge is scattered in a set of heterogeneous and interconnected modules. The original version of DFOL defined a set of primitives for the specification of a restricted subset of interconnections between knowledge modules. Despite this limitation, the ideas originally introduced in DFOL have influenced, in a significant manner, several works in the areas of distributed knowledge representation, heterogeneous knowledge integration, and semantic web, in the last 10+ years. The development of these works, together with the growth of interest in logical formalisms for the representation of distributed knowledge, have, in turn, fostered the development of a set of extensions and modifications of DFOL which have never been systematically described and published. In this paper we intend to sistematize and present, in a clear and comprehensive manner, this completely revised and extended version of DFOL. This version presents a general mechanism for the specification of interconnections between knowledge modules which takes into account the work done in applying the DFOL ideas in various fields of distributed knowledge representation, heterogeneous knowledge integration, and semantic web. The resulting general version of DFOL is therefore proposed as a clear formal tool for the representations and reasoning about distributed knowledge-base systems.