事务逻辑对象库语言

对象封装了结构和行为.对象数据库为大规模复杂应用提供良好的建模方法和实现手段.对象与逻辑结合导致目前对演绎对象库的研究.然而,这些研究基本上针对对象的结构描述,而很少涉及到对象的动态行为的描述.该文重点研究对象的动态行为,分析对象特征：继承和重载对事务语义的影响,并设计了一个事务对象库语言TOL(transaction object base language).首先分析TOL中的基本更新活动的特征,然后研究其事务的模型论语义.TOL模型论语义基于通路结构.     

DOL: 一个演绎对象库语言

演绎对象数据库是对象数据模型和演绎数据库集合的产物.它集成演绎数据库的查询能力和对象数据库的强大建模能力.DOL(deductive object base language)是作者设计的一种演绎对象库语言,它支持类、类层次、继承、集合、部分集、方法及重载和否定.文章着重研究继承、重载和复杂结构化值的交互关系.定义了压缩操作子和重载操作子.基于这两个操作子,定义了与经典逻辑程序类似的直接后承操作子,并研究其不定点性质.     

Design and Implementation of the ROL Deductive Object-Oriented Database System

ROL is a deductive object-oriented database system that has been implemented at the University of Regina. It provides a uniform rule-based declarative language for defining, manipulating and querying databases, which integrates important features of both deductive databases and object-oriented databases. It supports object identity, complex objects, classes, class hierarchies, multiple inheritance with overriding and blocking, and schema definition. It also supports structured values such as functor objects and sets, treating them as first class citizens, and providing powerful mechanisms for representing both partial and complete information about sets. This paper describes its design and implementation. An important novel feature of the implementation is that it combines top-down and bottom-up evaluation strategies and automatically selects a strategy based on the nature of the query and data in the database.     

Query by class,rule, and concept

The ideal query language for a knowledge base will probably never be found: easy formulation and easy evaluation of queries are two conflicting goals. Easy formulation asks for a flexible, expressive language near to human language or gestures. Easy evaluation of queries requires an effective mapping to machine code, which computes the correct answer in a finite number of steps. This article approaches the problem by a query language with three faces. The first projects queries to concepts of the knowledge representation language KL-One for easy formulation and readability. The second presents queries as rules of a deductive database with fixpoint semantics. The third presents queries as classes whose instances are the materialized answer (view) to the query. The methods for maintaining and updating the views are compiled from their deductive interpretation.     

On the declarative and procedural semantics of deductive object-oriented systems

We present declarative and procedural semantics for a deductive object-oriented language, Gulog. The declarative semantics is based on preferred minimal models. We describe both bottom-up and top-down query evaluation procedures and show that they are sound with respect to the declarative semantics. The results contribute to our understanding of the interaction of inheritance, overriding and deduction in the presence of both functional and set-valued methods, and multiple inheritance.     

Generalized production rules as a basis for integrating active anddeductive databases

The authors address the problem of providing a homogeneous framework for integrating, in a database environment, active rules, which allow the specification of actions to be executed whenever certain events take place, and deductive rules, which allow the specification of deductions in a logic programming style. Actually, it is widely recognized that both kinds of rules enhance the capabilities of database systems since they provide very natural mechanisms for the management of various important activities (e.g., knowledge representation, complex data manipulation, integrity constraint enforcement, view maintenance). However, in spite of their strong relationship, little work has been done on the unification of these powerful paradigms. They present a rule-based language with an event-driven semantics that allows programmers to express both active and deductive computations. The language is based on a new notion of production rules whose effect is both a change of state and an answer to a query. By using several examples, they show that this simple language schema allows one to uniformly define different computations on data, including complex data manipulations, deductive evaluations, and active rule processing. They define the semantics of the language and then describe the architecture of a preliminary implementation of the language. Finally, they report on the application and experience of using the language     

一个演绎对象数据库SD-DOOD的设计与实现

通过探寻面向对象数据库与知识库技术相结合的途径,研究演绎对象数据库系统实现的关键技术。以基于演绎数据库系统SD-DDBS,设计实现了一个演绎对象数据库系统原型SD-DOOD。系统支持类、类层次、对象、属性、方法、继承和封装等面向对象数据库系统的核心概念,支持演绎对象等演绎数据库的概念,提供了图形用户接口(GUI),便于用户进行创建、查询等操作。     

Likelog for flexible query answering

 Starting from unification based on similarity, a logic programming language, called LIKEness in LOGic (Likelog) is derived, thorougly relying on similarity. An operational semantics and a fix-point semantics of the language are defined, using an extension principle for fuzzy operators. The two approaches are proved to be related and a fuzzy extension of the least Herbrand model is given. One of the principal feature of such a logic programming language is to allow flexible query answering to deductive databases, which we show through an example. Moreover, we describe a system for web information retrieval through Likelog. I want to thank Ferrante Formato with whom I started and I continued this research and Prof. Giangiacomo Gerla for his great support and contribution given to this field.     

The Implementation of a Deductive Query Language Over an OODB

The ROCK and ROLL database system cleanly integrates deductive and object-oriented capabilities by defining an imperative programming language, ROCK, and a declarative, deductive language, ROLL, over a common object-oriented (OO) data model. Existing techniques for evaluation and optimization of deductive languages fail to address key requirements imposed by ROLL such as: strict typing; placement of deductive methods (predicates) within classes; encapsulation; overriding and late binding. This paper describes the task of implementing an evaluator and optimizer for ROLL, explaining how existing implementation techniques for deductive languages were adapted to meet these requirements and extended to support novel types of optimization.     

Transactions and updates in deductive databases

In this paper, we develop a new approach that provides a smooth integration of extensional updates and declarative query languages for deductive databases. The approach is based on a declarative specification of updates in rule bodies. Updates are not executed as soon as evaluated. Instead, they are collected and then applied to the database when the query evaluation is completed. We call this approach nonimmediate update semantics. We provide a top-down and equivalent bottom-up semantics which reflect the corresponding computation models. We also package set of updates into transactions and we provide a formal semantics for transactions. Then, in order to handle complex transactions, we extend the transaction language with control constructors still preserving formal semantics and semantics equivalence     

An Extension to GCWA and Query Evaluation for Disjunctive Deductive Databases

We present a simple and intuitive extension GCWA^G of the generalized closed world assumption (GCWA) from positive disjunctive deductive databases to general disjunctive deductive databases (with default negation). This semantics is defined in terms of unfounded sets and possesses an argumentation-theoretic characterization. We also provide a top-down procedure for GCWA^G, which is sound and complete with respect to GCWA^G. We investigate two query evaluation methods for GCWA^G: database partition, and database splitting. The basic idea of these methods is to divide the original deductive database into several smaller sub-databases and the query evaluation in the original database is transformed into the problem of query evaluation in smaller or simplified components. We prove that these two methods of query evaluation are all sound with respect to GCWA^G.     

A database of groups of prime-power order

The design, implementation and performance of TwoGroups, a deductive database for the 58,761 groups of order 2ⁿ, (n ≤ 8), is described. The system is implemented in NU-Prolog, a Prolog system with built-in functions for creating and using deductive databases. TwoGroups has a set-theoretic query language, which provides users with a familiar notation to access the data. The paper describes the data and its representation, the set-theoretic query language, its translator and optimiser, and the experiments on the performance of the database.     

ON TEMPORAL DEDUCTIVE DATABASES

This article introduces a temporal deductive database system featuring a logic programming language and an algebraic front-end. The language, called Temporal DATALOG, is an extension of DATALOG based on a linear-time temporal logic in which the flow of time is modeled by the set of natural numbers. Programs of Temporal DATALOG are considered as temporal deductive databases, specifying temporal relationships among data and providing base relations to the algebraic front-end. The minimum model of a given Temporal DATALOG program is regarded as the temporal database the program models intensionally. The algebraic front-end, called TRA, is a point-wise extension of the relational algebra upon the set of natural numbers. When needed during the evaluation of TRA expressions, slices of temporal relations over intervals can be retrieved from a given temporal deductive database by bottom-up evaluation strategies.
A modular extension of Temporal DATALOG is also proposed, through which temporal relations created during the evaluation of TRA expressions may be fed back to the deductive part for further manipulation. Modules therefore enable the algebra to have full access to the deductive capabilities of Temporal DATALOG and to extend it with nonstandard algebraic operators. This article also shows that the temporal operators of TRA can be simulated in Temporal DATALOG by program clauses.     

时态演绎数据库—模型与查询语言

时态演绎数据库是引入有效时间、事务时间概念的演绎数据库,能比较真实地反映现实世界的现象和发展状况,因此能满足现在的许多应用,如规划、决策支持系统、医疗信息系统等,因为这些应用不仅需要当前的数据,也需要历史数据     

Enriching the conceptual basis for query formulation through relationship semantics in databases

The rapid increase in end-user computing calls into question the suitability of existing database query languages (DBQLs). Because the typical DB end-user is not a DB specialist, it is essential that DBQLs use concepts that are as close as possible to those in the end-users’ cognitive mental model and adopt interface techniques that are suited to end-users’ abilities. Concept-based query languages are well suited for this. This realization has motivated further research in conceptual, or semantic, query approaches. However, the primary focus in this field has been on semantic query optimization, not on query formulation. In this study, we address ourselves to the problem of formulation of queries using concepts. We propose a concept-based query language, called the conceptual query language (CQL), which allows for the conceptual abstraction of database queries and exploits the rich semantics of data models to ease and facilitate query formulation.The CQL approach uses the relationship semantics of semantic data models to render transparent the technical complexities of existing DB query languages. Association semantics are also used to automatically construct query graphs and pseudo-natural language explanations of queries, and to generate SQL codes. A set theoretic formalism for conceptual queries is developed and used. This paper discusses the design of CQL, its expressive power, its implementation, and the strategies for CQL query processing. The implementation of a CQL prototype is briefly discussed in this paper. User experiments were carried out extensively and showed the advantage of CQL over alternative languages such as SQL.     

Word segmentation based on database semantics in NChiql

In this paper a novel word-segmentation algorithm is presented to delimit words in CHinese natural language queries in NChiql system,a Chinese natural language query interface to databases.Although there are sizalbe literatures on Chinese segmentation.,they cannot satisfy particular requirements in this system,The novel word-segmentation algorithm is based on the database semantics,namely Semantic Conceptual Model(SCM) for specific domain Knowledge,Based namely Semantic COnceptual Model(SCM) for specific domain knowledge,Based on SCM,the segmenter labels the database semantics to words directly,which eases the disambiguation and translation(from natural language to database query)in NChiql.