The deep symmetry of Linear Logic [18] makes it suitable for providing abstract models of computation, free from implementation details which are, by nature, oriented and non symmetrical. I propose here one such model, in the area of Logic Programming, where the basic computational principle is Computation = Proof search.

We present a new framework for amalgamating two successful programming paradigms: logic programming and object-oriented programming. From the former, we keep the declarative reading of programs. From the latter, we select two crucial notions: (i) the ability for objects to dynamically change their internal state during the computation; (ii) the structured representation of knowledge, generally obtained via inheritance graphs among classes of objects. We start with the approach, introduced in concurrent logic programming languages, which identifies objects with proof processes and object states with arguments occurring in the goals of a given process. This provides a clean, side-effect free account of the dynamic behavior of objects in terms of the search tree --- the only dynamic entity in logic programming languages. We integrate this view of objects with an extension of logic programming, which we call Linear Objects, based on the possibility of having multiple literals in the head of a program clause. This contains within itself the basis for a flexible form of inheritance, and maintains the constructive property of Prolog of returning definite answer substitutions as output of the proof of non-ground goals. The theoretical background for Linear Objects is Linear Logic, a logic recently introduced to provide a theoretical basis for the study of concurrency. We also show that Linear Objects can be considered a constructive restriction of full Classical Logic. We illustrate the expressive power of Linear Objects compared to Prolog by several examples from the object-oriented domain, but we also show that it can be used to provide elegant solutions for problems arising in the standard style of logic programming. 1

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We present a logic programming language that uses implications and universal quantifiers in goals and the bodies of clauses to provide a simple scoping mechanism for program clauses and constants. Within this language it is possible to define a simple notion of parametric module and local constant. Given this ability to structure programs, we explore how object-oriented programming, where objects are viewed as abstractions with behaviors, state, and inheritance, might be accommodated. To capture the notion of mutable state, we depart from the pure logic setting by adding a declaration that certain local predicates are deterministic (they succeed at most once). This declaration, along with a goal-continuation passing style of programming is adequate to model the state of objects. We also examine a few aspects of how having objects embedded in logic programming can be used to enrich the notion of object: for examples, objects may be partial (that is, may contain free variables) and non-d...

We discuss a declarative characterization of inheritance in logic programming. Our approach is inspired both by existing literature on denotational models for inheritance and by earlier work on a compositional definition of the semantics of logic Programming. We consider a general form of inheritance which is defined with an overriding semantics between inherited definitions and incorporates two different mechanisms known in the literature as static and dynamic inheritance. The result of our semantic reconstruction is an elegant framework which enables us to capture the compositional properties of inheritance and offers a uniform basis for the analysis of the different mechanisms we consider. 1

A deductive object-oriented database (DOOD) language, QUIXOT E, has been designed and developed for knowledge information processing applications such as natural language processing, legal reasoning, and genetic information processing in the Japanese Fifth Generation Computer System (FGCS) project and the FollowOn project. As knowledge information is different from conventional information, a new framework for database and knowledge-base management systems was required under such an environment. As a result, QUIXOT E has many unique features as a DOOD language and system. Focusing on such aspects in this paper, we describe specific features of QUIXOT E and discuss this approach. Further, we observe very briefly how such features are effective for knowledge information processing by showing some examples of our applications. 1 Introduction The Japanese Fifth Generation Computer System (FGCS) project developed various hardware and software for knowledge information processing systems u...

In this article we present the University of Evora's Integrated Information System (SIIUE), which is meant to model most of the information necessary for the management and day-to-day operation of an institution such as a public University. SIIUE is centered around a logicbased representation of all intervenients and processes, which is used to generate the more e#cient and specific representations for the actual use.

We propose a novel semantics for object-oriented deductive databases in the direction of F-logic to logically account for behavioral inheritance, conflict resolution in multiple inheritance hierarchies, and overriding. We introduce the ideas of withdrawal, locality, and inheritability of properties (i.e., methods and signatures). Exploiting these ideas, we develop a declarative semantics of behavioral inheritance and overriding without having to resort to non-monotonic reasoning. Conflict resolution in our model can be achieved both via specification and by detection. The possibility of specification based conflict resolution through withdrawal allows users to define inheritance preference. We present a formal account of the semantics of our language by defining a model theory, proof theory and a fixpoint theory. We also show that the different characterizations of our language are equivalent.

This paper discusses a multi-agent framework for the control of robot systems along with an integrated programming environment which takes advantage of it. An agent society is engaged in a competitive or cooperative interaction under a control metalevel while a particular agent represents the real-time robot machine. By virtue of the support of adequate tools, this schema well lends itself both to a general increase of robot programming capability and flexibility and to rapid protoyping of different architectural solutions. The overall programming environment is built upon the integration of a distributed, extended logic programming environment with a real-time RCCL-based robot server. It is also interfaced to a graphical simulator in which sensory driven tasks can be preliminary validated. An example of application of the environment to a simple test case concludes the paper. 1 Introduction Evolution of robot programming techniques and environments hardly is meeting the growing req...