Showing papers on "Graph database published in 1986"

Database integration in a distributed heterogeneous database system

Abstract: This paper describes the approach to database integration in a heterogeneous distributed database environment utilized by the Amoco Distributed Database System (ADDS). We start with the definition of the extended relational data model that is used by ADDS for database integration. We demonstrate various aspects of resolving possible data conflicts occurring in the database integration process. The ADDS query and data definition languages are defined and their expressive power is discussed. We conclude with presentation of a query conversion algorithm to convert a user data request into a set of queries against supported physical databases.

Set theoretic approaches to graph grammars

Abstract: This paper sketches the approaches of a certain branch of graph grammars mainly studied at Erlangen, Osnabruck, Koblenz and Aachen, West Germany. It is named set theoretic, or expression, or algorithmic approach of graph grammars, because its mathematical base is elementary set theory, expressions are used to denote embedding transformations, and the question of applicability and implementation always was regarded of equal importance as theoretical results.

Optimization of nested queries in a distributed relational database

Abstract: This paper describes how nested queries in the SQL language are processed by R*, an experimental adaptation to the distributed environment of the well-known centralized relational DBMS, System R. Nested queries are queries in which a predicate references the result of another query block (SELECT...FROM...WHERE...), called a subquery block (subQB). SubQBs may themselves contain one or more subQBs. Depending upon whether a subQB references values in other query blocks, it is processed differently, as either an Evaluate-at-Open or Evaluate-at-Application subQB type. Three tasks comprise execution of each query block: initiation, evaluation, and application. When the query’s tables are distributed among multiple sites, optimization of nested queries requires determining for each subQB: the site to perform each task, the protocols controlling interactions between those tasks, and the costs of each option, so that a minimal-cost plan can be chosen. R* optimizes each query block independently, “bottom up”, using only the cost, cardinal&y, and result site of the subQB in the optimization of its containing query block.

A domain-independent natural language database interface

Abstract: A DOMAIN-INDEPENDENT NATURAL LANGUAGE DATABASE INTERFACE Abstract of the Disclosure A domain-independent natural language interface for an existing entity-relationship database management system. Syntactically, it relies on an augmented phrase structure grammar which retains the convenience and efficiency of a semantic grammar while removing some of its ad hoc nature. More precisely, it is a syntactic domain-independent grammar augmented with semantic variables used by the parser to enforce the semantic correctness of a query; these semantic variables are only instantiated by a domain-dependent lexicon. Semantically, the interpretation of a query is in terms of general database navigation operations applied to domain-dependent parameters obtained from the lexicon. These operations apply to a virtual database, made of the actual database schema augmented with derived entity-sets. Navigation operations are eventually translated to actual database queries. - i -

Interpretation of Natural Language Database Queries Using Optimization Methods

Abstract: The automatic interpretation of natural language (English) database questions formulated by a user untrained in the technical aspects of database querying is an established problem in the field of artificial intelligence. State-of-the-art approaches involve the analysis of queries with syntactic and semantic grammars expressed in phrase structure grammer or transition network formalisms. With such methods difficulties exist with the detection and resolution of ambiguity, with the misinterpretation possibilities inherent with finite length look-ahead, and with the modification and extension of a mechanism for other sources of semantic knowledge. The potential of optimization techniques to solve these problems and interpret natural language database queries is examined.

Efficient algorithms for validating VLSI design database

Abstract: A generic application-independent validation of VLSI design database is presented. The detected violations are independent of the technology or manufacturing process and the verification is not a substitute for conventional Design Rule Checker (DRC) which is heavily process-dependent. The detection processing is done immediately after completing the VLSI graphic database and is based on a polygon-by-polygon analysis. The various violation types are described and the algorithms are demonstrated. The complexity of the algorithms is linear, compare to N*logN complexity in DRC algorithms. The advantages of using the up-front validation, especially when the database is hierarchical, are discussed.