Showing papers on "Graph database published in 1992"

A View Mechanism for Object-Oriented Databases

Abstract: In this paper, we present a view model for object-oriented databases that extends in various directions view models typical of relational databases. In particular, the definition language allows views to be defined that augment class definitions (by adding properties and methods), and that support a wide spectrum of schema modifications. Therefore, views represent a unified mechanism able to provide several functions, such as query shorthand, definitions of dynamic sets and partitions of classes, authorizations, schema changes and versions, object perspectives.

Building integrated software development environments. Part I: tool specification

Abstract: The conceptual modeling approach of the IPSEN (Integrated Project Support Environment) project for building highly integrated environments is based on using attributed graphs to model and implement arbitrary object structures, in particular all kinds of software documents and their relationships. A language based on graph grammars, called PROGRESS (PROgrammed Graph REwriting SyStems), and a suitable method for the application of this language, called graph grammar engineering, have been developed over the last ten years. This language and method are being extensively used for specifying the complex graph structures of internal document representations as well as for specifying the functionality of all tools (editors, browsers, analyzers, debuggers) working on these internal rpresentations. This paper explains the language and the method for applying the language based on a pragmatic nontrivial example of a software production process and its corresponding documents. In particular, it is shown why and how a graph grammar-based strongly typed language is perfectly suitable to formally specify highly integrated software tools. In addition, it is shown that the implementation of these tools (i.e., an environment composed of these tools) is systematically being derived from the formal specifications.

Introduction to graph grammars with applications to semantic networks

Abstract: In the first half of this paper, we give an introductory survey on graph grammars that provide rule-based mechanisms for generating, manipulating and analyzing graphs. In the second half, two potential applications of graph-grammar concepts to semantic networks are indicated.

Queries in Object-Oriented Database Systems

Abstract: A query language is an important component of any database system. In object-oriented data models, although messages serve to manipulate the database, a query language is still required to effectively deal with more complex situations and to facilitate associative access. In this paper, a query language for object-oriented data models is described. It handles both the structure as well as the behavior of objects. Not only the manipulation of existing objects, but also the creation of new objects and the introduction of new relationships are supported by the language. Equivalents to the five basic operations of the relational model as well as other additional operations such as one level project and nest are defined. Both the operands as well as the results of these operations are characterized as having a pair of sets -a set of objects and a set of message expressions (sequences of messages) applicable to them. The closure property is shown to be preserved in a natural way by the results of operations possessing the same characteristics as the operands in a query. It is shown that every class possesses the properties of an operand by defining a set of objects and deriving a set of message expressions for it. It is also shown how the super♪bclass relationships of the result of a query with its operands can be established and how the result can be placed persistently in the lattice as a class.

CGMA: A Novel Conceptual Graph Matching Algorithm

Abstract: A novel Conceptual Graph Matching Algorithm (CGMA) is proposed along with a knowledge base organization scheme. It allows the user to select the Degree of Matching and Degree of Inheritance to increase the user's satisfaction. A conceptual graph is represented in a special linear form (called U-Form) for CGMA. U-Form eliminates the necessity of explicit arcs in the graph to achieve the simplicity.

Generating ambiguous attributes for fuzzy queries

Abstract: A fuzzy querying model is proposed which can be realized in a front-end system connected to a host computer equipped with a conventional database management system. It is assumed in this model that queries have ambiguity, but the prepared data in a database have no ambiguity. >

An object-oriented database system for efficient information retrieval applications

Abstract: This dissertation deals with the application of object-oriented database techniques to the problem of storage and access of information retrieval (IR) data, especially data that can be organized as a graph, such as a thesaurus encoded in semantic networks, or hypertext collections. Even traditional IR models can use graph representations of documents and concepts. This dissertation reports the development of an object-oriented model called the LEND (Large External object-oriented Network Database) model. This model contains not only features found in a typical object-oriented model but also those that specifically are designed for graph-structured data. A query language is provided facilitating the specification of graph-oriented queries. A prototype LEND system has been implemented to test the model on realistic graph-structured data. It adopts an open system architecture and design, and is easily extensible, like the LEND model itself. The research result of suitable data structures and algorithms (a class of minimal perfect hashing functions) for the efficient implementation of the LEND model is also reported. These data structures and algorithms enable retrieval of a node or a set of nodes in an optimal fashion. Placement of a large graph on a disk is studied as well. The method developed permits efficient traversal of graphs.

Challenges in graph-based relational data visualization

Abstract: During recent years we have witnessed a growing trend toward the use of visual interfaces to view and query databases. The graph topovisual formalism is particularly well-suited for depicting relational data. The vertices of a directed graph represent a set of entities, while arcs represent relationships among the entities. This paper studies the functional requirements of a hypothetical graph visualization facility (GVF) by surveying past work in related areas and by describing challenging problems that must be addressed before such a system can be realized. Our contribution, therefore, is twofold: we present a unique holistic approach, which, in turn, gives rise to a number of interesting research problems.

Processing hierarchical queries in heterogeneous environment

Abstract: The authors investigate principles of translating relational queries to hierarchical queries. Instead of using a specific hierarchical database system they abstract a generic hierarchical database system (GHDBS) which has properties common to database systems whose schema contain hierarchical structures. Principles of query translation with GHDBS as the receiving database system are developed. Rules that guarantee the correctness of the translated queries are described. Rules are provided that can guarantee a minimum number of target queries in a case when a user-submitted source query needs to be translated to multiple target queries. >

Multi-query processing within a distributed deductive database

Abstract: Because the needs and requirements of database users have continued to grow and change, we are forced to constantly look for new and more efficient ways to handle database access. One way to approach the database problem is through the use of distributed processing. Although the significance of distributed processing has been recognized in a variety of application domains for several years, there remains a substantial amount of work yet to be accomplished to make this a marketable and practical solution in the area of general deductive databases. The main problem is the lack of a general model that is capable of harnessing the potential power and flexibility of a distributed system, in which each machine has processing capabilities. Therefore, our focus is on the integration of deduction and databases in a distributed environment. Our view of a distributed deductive database system is one in which data is distributed across many computers, or workstations, which are in a somewhat geographically localized vicinity (e.g. a cluster of offices, or within a building). The workstations are connected via a communication network. Another aspect of the system is that it is main memory resident. With the availability of very large, relatively inexpensive main memories, it is becoming possible to keep large databases resident in main memory. Retrieval time in this situation will be faster because no disk accesses will have to take place. In our system the rules and relations of the DDB are precompiled into a graph, which we are calling the Extended Predicate Connection Graph (EPCG). A partitioning process takes place on this graph to divide it into a suitable number of clusters. Each cluster, or partition, is then assigned to a processing node in our share-nothing hardware system. Each partition contains one or more relations as well as the set of rules relevant to those relations. By partitioning the Extended Predicate Connection Graph and distributing the partitions, we are able to process user queries in a distributed fashion.

Efficient management of materialized path aggregation

Abstract: A data structure is given for storing materialized aggregated path information such that the evaluation of a traversal recursion that consists of the traversal of an acyclic directed graph with path aggregation is simply a look-up. The retrieval time is proportional to the size of the answer. Using the data structure, insertions and deletions of edges can also be performed efficiently. The scheme is effective in retrieval-intensive environments. The scheme is also easily extended to multiple-processor environments. >

Large-scale graph decomposing device

Abstract: PURPOSE:To compactly decompose and express the highly related large-scale graph structure data. CONSTITUTION:A graph data input means 1 is provided to apply the input/initial processing to the subject graph structure data together with a cost calculation means 2 which performs the cost calculation to the data obtained from the means 1 for execution of the abstracted decomposition, a membership store means 3 which performs the clustering and stores the corresponding relation among the intensive nodes corresponding much to one to each node based on the results obtained from both means 1 and 2, an intensive graph store means 4 which describes the relation of intensive nodes, and an exceptional graph store means 5 which stores the exceptional input data. Then an output means 6 transfers or expresses those information stored in the means 3, 4 and 5 respectively.