This paper presents the constraint system FT, which we feel is an intriguing alternative to Herbrand both theoretically and practically. As does Herbrand, FT provides a universal data structure based on trees. However, the trees of FT (called feature trees) are more general than the trees of Herbrand (called constructor trees), and the constraints of FT are finer grained and of different expressivity. The basic notion of FT are functional attributes called features, which provide for record-like descriptions of data avoiding the overspecification intrinsic in Herbrand's constructor-based descriptions. The feature tree structure fixes an algebraic semantics for FT. We will also establish a logical semantics, which is given by three axiom schemes fixing the first-order theory FT. FT is a constraint system for logic programming, providing a test for unsatisfiability, and a test for entailment between constraints, which is needed for advanced control mechanisms. The two major technical con...

We introduce a constraint system called FT. This system offers a theoretical and practical alternative to the usual Herbrand system of constraints over constructor trees. Like Herbrand, FT provides a universal data structure based on trees. However, the trees of FT (called feature trees) are more general than the constructor trees of Herbrand, and the constraints of FT are of finer grain and of different expressiveness. The essential novelty of FT is provided by functional attributes called features which allow representing data as extensible records, a more flexible way than that offered by Herbrand's fixed arity constructors. The feature tree structure determines an algebraic semantics for FT. We establish a logical semantics thanks to three axiom schemes presenting the first-order theory FT. We propose using FT as a constraint system for logic programming. We provide a test for constraint unsatisfiability, and a test for constraint entailment. The former corresponds to unification ...

Knowledge representation languages and knowledgebases play a key role in knowledge information processing systems. In order to support such systems, we have developed a knowledge representation language, QUI- XOT E, a database management system, Kappa, as the database engine, some applications on QUIXOT E and Kappa, and two experimental systems for more flexible control mechanisms. The whole system can be considered as under the framework of deductive object-oriented databases (DOODs) from a database point of view. On the other hand, from the viewpoint of the many similarities between database and natural language processing, it can also be considered to support situated inference in the sense of situation theory. Our applications have both of these features: molecular biological databases and a legal reasoning system, TRIAL, for DOOD and a temporal inference system for situated inference. For efficient and flexible control mechanisms, we have developed two systems: cu-Prolog based ...

Feature trees are the formal basis for algorithms manipulating record like structures in constraint programming, computational linguistics and in concrete applications like software configuration management. Feature trees model records, and constraints over feature trees yield extensible and modular record descriptions. We introduce the constraint system FT of ordering constraints interpreted over feature trees. Under the view that feature trees represent symbolic information, the relation corresponds to the information ordering ("carries less information than"). We present two algorithms in cubic time, one for the satisfiability problem and one for the entailment problem of FT . We show that FT has the independence property. We are thus able to handle negative conjuncts via entailment and obtain a cubic algorithm that decides the satisfiability of conjunctions of positive and negated ordering constraints over feature trees. Furthermore, we reduce the satisfiability problem of Dorre's weak subsumption constraints to the satisfiability problem of FT and improve the complexity bound for solving weak subsumption constraints from O(n^5) to O(n³).

The language FT of ordering constraints over feature trees has been introduced as an extension of the system FT of equality constraints over feature trees. While the first-order theory of FT is well understood, only few decidability results are known for the first-order theory of FT . We introduce a new method for proving the decidability of fragments of the first-order theory of FT . This method is based on reduction to second order monadic logic that is decidable according to Rabin's famous tree theorem. The method applies to any fragment of the first-order theory of FT for which one can change the model towards sufficiently labeled feature trees -- a class of trees that we introduce. As we show, the first order-theory of ordering constraints over sufficiently labeled feature trees is equivalent to second-order monadic logic (S2S for infinite and WS2S for finite feature trees). We apply our method for proving that entailment of FT with existential quantifiers j 1 j=9x 1 : : :9x n j 2 is decidable. Previous results were restricted to entailment without existential quantifiers which can be solved in cubic time. Meanwhile, entailment with existential quantifiers has been shown PSPACE-complete (for finite and infinite feature trees respectively).

In the FGCS project and its Follow-on project, we have designed and developed a nested relational database management system, Kappa, a deductive objectoriented database (DOOD) language (or a knowledge representation language), QUIXOT E, and a heterogeneous distributed cooperative problem solving system, Helios, for knowledge information processing applications. In this paper, from the viewpoint of database and knowledge-base management systems, I overview their objectives and features, and summarize their contributions. Especially. I focus mainly on their language aspects rather than systems. Further, by reflecting their experiences, I discuss some directions of future database from an application point of view. 1 Introduction In the FGCS (Fifth Generation Computer Systems, 1982-1993) project[Kurozumi 92] and its Follow-on project (1993-1995)[Uchida et al 93], we have been engaged in various knowledge information processing applications such as natural language processing, genetic in...

CONTENTS i Contents 1 Introduction 1 2 Organic Programming 2 3 GAEA Language 4 3.1 Programs : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.1 Terms : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.2 Constants : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.3 Variables : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.4 Strings : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.5 Tuples : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.6 Lists : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.7 Infons : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.8 Clauses : : : :

CONTENTS i Contents 1 Introduction 1 2 Organic Programming 2 3 GAEA Language 4 3.1 Programs : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.1 Terms : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.2 Constants : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.3 Variables : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 3.1.4 Strings : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.5 Tuples : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.6 Lists : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.7 Infons : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 3.1.8 Clauses : : : :