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Object-oriented database schema analysis and inheritance processing: A graph-theoretic approach

DATA & KNOWLEDGE ENGINEERING 1997年第2期24卷 157-181页

作者： Formica, A Groger, HD Missikoff, M CNR IST ANAL SISTEMI & INFORMATI-00185 ROMEITALY SZECHENYI COLL H-9026 GYORHUNGARY

In this paper we address the inheritance process in the context of strongly typed Object-oriented database (OODB) systems, allowing multiple inheritance and overriding. For such powerful systems, it is important to analyse the inheritance hierarchy to identify a number of significant properties. The first, schema consistency, is connected to the inheritance conflicts. In the presence of an unsolvable inheritance conflict there is a contradiction in the schema. The second property is related to the termination of the inheritance process. We expect that all the subtypes in the schema, if consistent, can be rewritten in expanded form, after inheritance, in a finite time. Schemas that guarantee these two formal properties will be referred to as correct schemas. In the paper a graph-theoretic method is provided, aimed at supporting the designer in checking the correctness and deriving the expanded form of a schema. Furthermore, from the analysis of the complexity of the inheritance process, a third formal property has been defined, concerning the degree of compactness achievable in a schema, by using inheritance hierarchies. In particular, a class of schemas has been defined, referred to as logarithmic schemas, whose expanded forms, after inheritance, become exponential in the size of the original schemas.

关键词： object-oriented databases multiple inheritance inheritance process inheritance conflicts recursive schemas schema consistency subtyping substitutivity database design

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Incremental inheritance mechanism and its message evaluation method

Incremental inheritance mechanism and its message evaluation...

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3rd Basque International Workshop on Information Technology (BIWIT 97) - Data Management Systems

作者： Benattou, M Lakhal, L Universite Blaise Pascal Clermont-Ferrand II Aubiere France

ISBN: (纸本)0818680504

The semantics of inheritance is based on subtyping. Several authors have shown that the subtype relation is insufficient to explain the inheritance mechanism in object oriented approach. inheritance is an incremental mechanism for software development, based on modification. This approach was introduced by W. R. Cook. The aim of this paper is to present an incremental formal model of single and multiple inheritance, based on the wrapping concept. The model is based upon an intuitive explanation of the proper use and purpose of inheritance, and is essentially dedicated to dynamic (i.e. run-time) inheritance of properties, for OODBMS. The denotational semantics method proposed using the incremental model of inheritance, allows dynamic message evaluation.

关键词： single inheritance multiple inheritance name conflict values conflict incremental mechanism modification wrapping linearisation

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Dynamic reasoning with qualified syllogisms

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ARTIFICIAL INTELLIGENCE 1997年第1-2期93卷 103-167页

作者： Schwartz, DG Department of Computer Science Florida State University Tallahassee FL 32306-4019 USA

A qualified syllogism is a classical Aristotelean syllogism that has been ''qualified'' through the use of fuzzy quantifiers, likelihood modifiers, and usuality modifiers, e.g., ''Most birds can fly;Tweety is a bird;therefore, it is likely that Tweety can fly.'' This paper introduces a formal logic Q of such syllogisms and shows how this may re employed in a system of nonmonotonic reasoning. In process are defined the notions of path logic and dynamic reasoning system (DRS). The former is an adaptation of the conventional formal system which explicitly portrays reasoning as an activity that takes place in time. The latter consists of a path logic together with a multiple-inheritance hierarchy. The hierarchy duplicates some of the information recorded in the path logic, but additionally provides an extralogical specificity relation. The system uses typed predicates to formally distinguish between properties and kinds of things. The effectiveness of the approach is demonstrated through analysis of several ''puzzles'' that have appeared previously in the literature, e.g., Tweety the Bird, Clyde the Elephant, and the Nixon Diamond. It is also outlined how the DRS framework accommodates other reasoning techniques-in particular, predicate circumscription, a ''localized'' version of default logic, a variant of nonmonotonic logic, and reason maintenance. Furthermore it is seen that the same framework accomodates a new formulation of the notion of unless. A concluding section discusses the relevance of these systems to the well-known frame problem. (C) 1997 Elsevier Science B.V.

关键词： default reasoning dynamic reasoning systems fuzzy likelihood fuzzy probabilities fuzzy quantifiers multiple inheritance nonmonotonic reasoning qualified syllogisms the frame problem unless

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Enhanced reusability via polymorphic additive virtual methods in C++

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INFORMATION AND SOFTWARE TECHNOLOGY 1997年第6期39卷 403-415页

作者： Chattamvelli, R Saiedian, H Department of Computer Science University of Nebraska at Omaha Omaha NE 68182-0500 USA

The virtual method is a useful concept in polymorphic behavior of object-oriented programs. By making a method virtual in a class, all classes derived from that class are allowed to modify or enhance the definition of the method (while retaining its original signature) providing one kind of polymorphism. In this article, we explore the virtues of virtual methods and introduce different ways of implementing additive virtual methods in C++. The concepts presented can find applications in shared software libraries, integrating software applications, and distributed computing. (C) 1997 Elsevier Science B.V.

关键词： additive methods assistant functions late binding multiple inheritance virtual tables

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A configurable type hierarchy index for OODB

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VLDB Journal 1997年第4期6卷 312-332页

作者： Mueck, Thomas A. Polaschek, Martin L. Abteilung für Data Engineering Universität Wien A-1010 Wien Rathausstr. 19/4 Austria

With respect to the specific requirements of advanced OODB applications, index data structures for type hierarchies in OODBMS have to provide efficient support for multiattribute queries and have to allow index optimization for a particular query profile. We describe the multikey type index and an efficient implementation of this indexing scheme. It meets both requirements: in addition to its multiattribute query capabilities it is designed as a mediator between two standard design alternatives, key-grouping and type-grouping. A prerequisite for the multikey type index is a linearization algorithm which maps type hierarchies to linearly ordered attribute domains in such a way that each subhierarchy is represented by an interval of this domain. The algorithm extends previous results with respect to multiple inheritance. The subsequent evaluation of our proposal focuses on storage space overhead as well as on the number of disk I/O operations needed for query execution. The analytical results for the multikey type index are compared to previously published figures for well-known single-key search structures. The comparison clearly shows the superiority of the multikey type index for a large class of query profiles.

关键词： Access methods Indexing multiple inheritance OODB Type hierarchies

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ACQUISITION AND VALIDATION OF COMPLEX OBJECT DATABASE SCHEMATA SUPPORTING multiple inheritance

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APPLIED INTELLIGENCE 1994年第2期4卷 185-203页

作者： BERGAMASCHI, S NEBEL, B GERMAN RES CTR ARTIFICIAL INTELLIGENCE D-66123 SAARBRUCKENGERMANY

We present an intelligent tool for the acquisition of object-oriented schemata supporting multiple inheritance, which preserves taxonomy coherence and performs taxonomic inferences. Its theoretical framework is based on terminological logics, which have been developed in the area of artificial intelligence. The framework includes a rigorous formalization-of complex objects, which is able to express cyclic references on the schema and instance level;a subsumption algorithm, which computes all implied specialization relationships between types;and an algorithm to detect incoherent types, i.e., necessarily empty types. Using results from formal analyses of knowledge representation languages, we show that subsumption and incoherence detection are computationally intractable from a theoretical point of view. However, the problems appear to be feasible in almost all practical cases.

关键词： KNOWLEDGE REPRESENTATION TAXONOMIC REASONING OBJECT-ORIENTED SCHEMATA multiple inheritance

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Supporting explicit disambiguation of multi-methods 10th

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Proceedings of the 1996 10th European Conference on Object-Oriented Programming, ECOOP'96

作者： Amiel, Eric Dujardin, Eric NatSoft Air Center Geneve 1214 Switzerland INRIA Projet RODIN BP 78153 Le Chesnay Cedex 105 France

ISBN: (纸本)9783540614395

multiple inheritance and multiple dispatching are two sources of ambiguities in object-oriented languages. Solving ambiguities can be performed automatically, using techniques such as totally ordering the supertypes of each type or taking the order of the methods' arguments into account. Such implicit disambiguation has the drawback of being difficult to understand by the programmer and hiding programming errors. Conversely, solving ambiguities can be left up to the explicit intervention of the programmer. The most common explicit disambiguation technique in existing systems consists in defining new methods for ambiguous invocations. However, finding ambiguities and adding as few methods as possible is a difficult task, especially in multi-method systems. In this paper, we propose a tool to help the programmer solve multi-methods ambiguities. We show that there always exists a unique minimal set of method redefinitions that explicitly disambiguate a set of multi-methods. The tool offers two modes: batch, directly yielding the disambiguation set, or interactive, one signature of the disambiguation set at a time, allowing the programmer to either accept the method redefinition or to solve the ambiguity in any other way, which restarts the disambiguation algorithm. In both modes, for each method that is to be added, the programmer is given the set of methods that caused the ambiguity as an explanation. © Springer-Verlag Berlin Heidelberg 1996.

关键词： Ambiguities Method dispatch Multi-methods multiple inheritance

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Denotational Semantics of a Simple Model of Eiffel

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Journal of Computer Science & Technology 1995年第3期10卷 214-226页

作者：瞿裕忠王志坚徐家福 InstituteofComputerSoftware NanjingUniversityNanjing210093

A simple abstract model of Eiffel is introduced, and its denotational seman-tics is defined using VDM style. A static analysis approach is presented to treatmultiple inheritance and renaming mechanism. Within the framework of deno-tational semantics iatroduced in this paper, the key features of Eiffel, such asidentification, classification, multiple inheritance, polymorphism and dynamicbinding, can be adequately characterized.

关键词： Eiffel language multiple inheritance renaming static analysis semantic domains semantic functions

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MODELING CLASS HIERARCHIES IN THE FUZZY OBJECT-ORIENTED DATA MODEL

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FUZZY SETS AND SYSTEMS 1993年第3期60卷 259-272页

作者： GEORGE, R BUCKLES, BP PETRY, FE TULANE UNIV DEPT COMP SCICTR INTELLIGENT & KNOWLEDGE BASED SYSTNEW ORLEANSLA 70118 CLARK ATLANTA UNIV DEPT COMP & INFORMAT SCIATLANTAGA

In this paper we describe a fuzzy logic based approach to modelling uncertainty in class hierarchies. It is shown that the traditional view of class hierarchies is subsumed in this model as a special case. The problem of multiple inheritance in class hierarchies is discussed and analyzed. The membership value derivations in the inheritance hierarchy reflects the degree of fuzziness existing in the data values and the semantics of the situation being modelled. Thus a more realistic modelling of the universe of discourse is possible through this approach. This model is compatible with existing object-oriented data models.

关键词： CLASS HIERARCHIES SIMILARITY RELATION inheritance multiple inheritance DATABASES OBJECT-ORIENTED DATABASES

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OBJECT-ORIENTATION AND THE SQL STANDARD

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COMPUTER STANDARDS & INTERFACES 1993年第2-3期15卷 287-300页

作者： KULKARNI, KG TANDEM COMP INC CUPERTINOCA 95014

The database language standard, SQL, adopted by both ANSI and ISO, is now well established as a language for developing database applications. The SQL standard has been evolving ever since its first adoption in 1986, with new revisions being announced every three years. The latest revision (SQL-92) has just been announced by both ANSI and ISO. Currently, work is underway on the next revision, SQL3, which is expected in 1995-96 timeframe. A major focus of SQL3 effort is to incorporate an object-oriented type system while maintaining strict upward compatibility with SQL-92. The type system of SQL3 is based on concepts such as abstract data types, object identity, polymorphism, subtypes-supertypes, parameterized types, dynamic binding, etc. In this paper, we report on the current status of SQL-3 type system.

关键词： ABSTRACT DATA TYPES ANSI C++ COBOL DATABASE LANGUAGES DYNAMIC BINDING ISO NESTED RELATIONS NON-1ST NORMAL FORM RELATIONS OBJECT IDENTITY multiple inheritance MULTISETS OBJECT-ORIENTED DATABASE SYSTEMS OVERLOADING PARAMETERIZED TYPES POLYMORPHISM QUERY LANGUAGES RELATIONAL DATABASE SYSTEMS SEMANTIC DATA MODELS SQL SQL-86 SQL-89 SQL-92 SQL3 TYPE TEMPLATES

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