Showing papers on "Graph database published in 1994"

GraphDB: Modeling and Querying Graphs in Databases

Abstract: We propose a data model and query language that integrates an explicit modeling and querying of graphs smoothly into a standard database environment. For standard applications, some key features of object-oriented modeling are offered such as object classes organized into a hierarchy, object identity, and attributes referencing objects. Querying can be done in a familiar style with a derive statement that can be used like a select ... from ... where. On the other hand, the model allows for an explicit representation of graphs by partitioning object classes into simple classes, link classes, and path classes whose objects can be viewed as nodes, edges, and explicitly stored paths of a graph (which is the whole database instance). For querying graphs, the derive statement has an extended meaning in that it allows one to refer to subgraphs of the database graph. A powerful rewrite operation is offered for the manipulation of heterogeneous sequences of objects which often occur as a result of accessing the database graph. Additionally there are special graph operations like determining a shortest path or a subgraph and the model is extensible by such operations. Besides being attractive for standard applications, the model permits a natural representation and sophisticated querying of networks, in particular of spatially embedded networks like highways, public transport, etc. This work was supported by the ESPRIT Basic Research Project 6881 AMUSING

A graph-oriented object database model

Abstract: A graph-oriented object database model (GOOD) is introduced as a theoretical basis for database systems in which manipulation as well as conceptual representation of data is transparently graph-based. In the GOOD model, the scheme as well as the instance of an object database is represented by a graph, and the data manipulation is expressed by graph transformations. These graph transformations are described using five basic operations and a method construct, all with a natural semantics. The basic operations add and delete objects and edges as a function of the matchings of a pattern. The expressiveness of the model in terms of object-oriented modeling and data manipulation power is investigated. >

Method for storing and retrieving images in/from a database

Abstract: A method for storing, processing, and retrieving images in/from a graphic database. The graphic database is a digital database which is created by converting an original image into a digital format and arranging and organizing the digital format so as to identify elements of the converted image. The graphic database is so arranged and organized as to enable the identifiable elements of the converted image to be searched and displayed with the look and format of the original image.

The Grasper-CL graph management system

Abstract: Grasper-CL is a system for manipulating and displaying graphs, and for building graph-based user interfaces for application programs It is implemented in COMMON LISP and CLIM, and has been proven by use in a number of applications Grasper-CL includes several advances in graph drawing It contains a graph abstract datatype plus a comprehensive and novel language of operations on that datatype The appearance of Grasper-CL graphs can be tailored by a wide variety of shape parameters that allow the application to customize the display of nodes and edges for different domains Default values for shape parameters can be established at several levels Grasper-CL employs a toolbox approach to graph layout: the system contains a suite of graph layout algorithms that can be applied individually, or in combination to produce hierarchical graph layouts The system also contains an interactive graph browser

Exploiting the Induced Order on Type-Labeled Graphs for Fast Knowledge Retrieval

Abstract: The graph structure of a conceptual graph can be used for efficient retrieval in complex (graphical) object databases. The aim is to replace most graph matching with efficient operations on precompiled codes for graphs. The unlabeled graph or “skeleton” of a type-labeled conceptual graph (without negated contexts) can be used as a filter for matching, subsumption testing, and unification. For two type-labeled graphs to match, their skeletons must first match. One type-labeled graph can subsume another only if its skeleton is included in that of the other. An skeleton-inclusion hierarchy can be constructed for a useful set of all possible skeletons up to a certain size. That hierarchy is then embedded in a Boolean lattice of bit-strings. Expensive graph comparison operations are traded for very fast bit-string logic operations on the codes. New graphs can be encoded at run time without recompiling the whole hierarchy: having found a graph's structural type, we then use it to hash to the code encoding the poset of all possible type-labeled graphs ordered by subsumption. Some of the order in that poset comes from the subgraph inclusion factor while other order comes from the “typelattice” (on concept-labels) factor. We show how they relate. We are investigating the bounds on code length and new methods of factorisation of conceptual graph databases.

GraphDB: A Data Model and Query Language for Graphs in Databases

Abstract: We propose a data model and query language that integrates an explicit modeling and querying of graphs smoothly into a standard database environment. For standard applications, some key features of object-oriented modeling are offered such as object classes organized into a hierarchy, object identity, and attributes referencing objects. Querying can be done in a familiar style with a derive statement that can be used like a select ... from ... where. On the other hand, the model allows for an explicit representation of graphs by partitioning object classes into simple classes, link classes, and path classes whose objects can be viewed as nodes, edges, and explicitly stored paths of a graph (which is the whole databasc instance). For querying graphs, the derive statement has an extended meaning in that it allows one to refer to subgraphs of the database graph. A powerful rewrite operation is offered for the manipulation of hetereogeneous sequences of objects whichoften occur as a result of accessing the database graph. Additionally there are special graph operations like determining a shortest path or a subgraph and the model is extensible by such operations. It is possible to compute additions to the database graph as well as restrictions in a query. Besides being attractive for standard applications, the model permits a natural representation and sophisticated querying of networks, in particular of spatially embedded networks like highways, public transport, etc. The GraphDB model is meant to be implemented; system architecture and a representation and query processing strategy are outlined in the paper.

Database Graph Views: A Practical Model to Manage Persistent Graphs

Abstract: Advanced technical applications like routing systems or electrical network management systems introduce the need for complex manipulations of large size graphs. Efficiently supporting this requirement is now regarded as a key feature of future database systems. This paper proposes an abstraction mechanism, called Database Graph View, to define and manipulate various kinds of graphs stored in either relational, object oriented or file systems. A database graph view provides a functional definition of a graph which allows its manipulation independently of its physical organization. Derivation operators are proposed to define new graph views upon existing ones. These operators permit the composition, in a single graph view, of graphs having different node and edge types and different implementations. The graph view mechanism comes with an execution model where both set-oriented and pipelined execution of graph operators can be expressed. The graph view operators form a library which can be integrated in database systems or applications managing persistent data with no repercussion on the data organization.

New graph search techniques for speech recognition

Abstract: We present a new multi-pass approach to the search problem in speech recognition. It builds on the 1-phone lookahead property which enables all of the time alignment for the first forward pass to be performed in pre-processing stage. This feature allows us to view the first forward pass a classical graph search problem and to apply powerful searching techniques that have not previously been used in speech recognition. >

A Paradigm For Natural Language Explanation Of Database Queries: A Semantic Data Model Approach

Abstract: Although the increasing pervasiveness of end-user computing has made concerns with database interfaces increasingly more important, paradoxically, there does not seem to be sufficient research into database interfaces for end-user computing. A much needed but neglected enrichment of database systems is an interface that provides the user with automatic feedback in the form of an explanation of how the database management system interprets user-specified queries. The study presented in this paper proposes an approach that exploits the rich semantics of graphical semantic data models to construct restricted natural language explanations of database queries that are specified in a very high-level declarative form. These interpretations of the specified query represent the system’s “understanding†of the query, and are returned to the user for validation.

Database Graph Views: A Practical Model to Manage Persistent Graphs.

Abstract: Advanced technical applications like routing systems or electrical network management systems introduce the need for complex manipulations of large size graphs. Efficiently supporting this requirement is now regarded as a key feature of future database systems. This paper proposes an abstraction mechanism, called Database Graph View, to define and manipulate various kinds of graphs stored in either relational, object oriented or file systems. A database graph view provides a functional definition of a graph which allows its manipulation independently of its physical organization. Derivation operators are proposed to define new graph views upon existing ones. These operators permit the composition, in a single graph view, of graphs having different node and edge types and different implementations. The graph view mechanism comes with an execution model where both set-oriented and pipelined execution of graph operators can be expressed. The graph view operators form a library which can be integrated in database systems or applications managing persistent data with no repercussion on the data organization.

Spatial data traversal in road map databases: a graph indexing approach

Abstract: Spatial data are found in geographic information systems such as digital road map databases where city and road attributes are associated with nodes and links in a directed graph. Queries on spatial data are expensive because of the recursive property of graph traversal. We propose a graph indexing technique to expedite spatial queries where the graph topology remains relatively stationary. Using a probabilistic analysis, this paper shows that the graph indexing technique significantly improves the efficiency of constrained spatial queries.

Advances in graph drawing

Abstract: Graph drawing addresses the problem of constructing geometric representations of abstract graphs and networks. It is an emerging area of research that combines flavors of topological graph theory and computational geometry. The automatic generation of drawings of graphs has important applications in key computer technologies such as software engineering, database design, visual interfaces, and computer-aided-design. This paper surveys recent results of the authors on graph drawing and overviews various research trends in the area.

Standardizing and Interfacing Relational Databases Using Conceptual Graphs

Abstract: In order to apply Conceptual Graphs to Relational Databases [Bo&al93], we developed the notion of sets associated to a CG, introduced built-in relations to express general conditions for joining relations, and then began to sketch the ability of a CG base to allow a uniform representation of schemata, data and queries in a Database. Using this formalism, we now show how to express nested selects, and how it is possible to process incomplete queries, helping the user to query the Database without precisely knowing its structure. As these first-level Database concepts may be uniformly represented using CGs, our centre of interest is now higher-level notions such as queries upon queries. CGs may be used to represent not only the basic Database concepts, but the entire Database, including Database management operations.

Inference Systems for Conceptual Graph Programs

Abstract: Conceptual graph programs are a kind of order-sorted logic programs based on conceptual graphs. In this paper, we investigate various approaches towards formal inference systems for conceptual graph programs and propose two different deduction procedures. The first one, called the CG-resolution, is a refutation-based resolution procedure that is somewhat analogous in approach to the SLD-resolution of first-order predicate logic. The second one, called the CGF-derivaton, is a forward derivation based deduction procedure. Both procedures are sound with respect to the declarative semantics of conceptual graph programs.

Extending SQL with graph matching and set covering for decision support applications

Abstract: Graph matching, set covering, and partitioning problems are both theoretically and practically important in decision support systems. Numerous decision support applications have been modeled as graph matching, set covering, and partitioning problems. These include applications in the areas of task assignment, marriage problem, airline crew scheduling, truck deliveries or vehicle routing, political redistricting, and the like. Currently, these applications are supported through programs written in external (to the database system) programming languages that use only the data in the database system. Thus, decision makers or application programmers require extra effort to get required decision support information. As opposed to database systems, the purpose of a model management system (MMS) is to make a wide variety of models available to decision makers so they can apply these models without having to become involved in technical and/or procedural aspects of implementation. The goal of this research is to integrate database systems and model systems for zero-one integer programming problems especially concerning graph matching, set covering, and partitioning problems. Users utilize a single integrated language for both problem formulation and model execution. In order to achieve this goal, we extend relational operators and the query language SQL. The relational operators are extended with six operators, namely, match, maxmatch, cover, mincover, partition, and minpartition. Some of these operators may take a very long time to find an optimal solution. In this article, we adopted genetic algorithms to find a near-optimal solution of this kind of operators. We found they performed well both on the computational effort and on the quality of the solutions through a variety of test problems. These algorithms are bounded by a polynomial time. Therefore, they enable a DBMS to respond to queries involving proposed operators in a restricted amount of time.

Performances of clustering policies in object bases

Abstract: In this paper, we address the problem of clustering graphs in object-oriented databases. Unlike previous studies which focused only on a workload consisting of a single operation, this study tackles the problem when the workload is a set of operations (method and queries) that occur with a certain probability. Thus, the goal is to minimize the expected cost of an operation in the workload, while maintaining a similarly low cost for each individual operation class.To this end, we present a new clustering policy based on the nearest-neighbor graph partitioning algorithm. We then demonstrate that this policy provides considerable gains when compared to a suite of well-known clustering policies proposed in the literature. Our results are based on two widely referenced object-oriented database benchmarks; namely, the Tektronix HyperModel and OO7.

A Unified Framework for Indexing in Database Systems

Abstract: Several types of data organizations have been proposed in the literature for object-oriented and relational databases. In studying these organizations, there appears to be no underlying common basis on which they can be compared. Many of these organizations impose restrictions on their applicability that seem unnecessary or ad-hoc. We present a unified framework for physical database storage. We show that most existing data organizations follow naturally as special cases of this framework. Furthermore, this framework permits the specification of new types of data organization that have not been proposed or that cannot be described in existing systems, yet appear to be useful.

Functional Graph Algorithms with Depth-First Search (Preliminary Summary)

Abstract: Performing a depth-first search of a graph is one of the fundamental approaches for solving a variety of graph algorithms. Implementing depth- first search efficiently in a pure functional language has only become possible with the advent of imperative functional programming. In this paper we mix the techniques of pure functional programming in the same cauldron as depth-first search to yield a more lucid approach to viewing a variety of graph algorithms. This claim will be illustrated with several examples.

Database mining in the architecture of a semantic pre-processor for state-aware query optimization

Abstract: Most applications of in database mining at present seem to be concentrated around the discovery of knowledge for application-oriented decision support. In this paper we describe a tool for enhancing the performance of the database management system itself using semantics captured by database mining techniques. We investigate the use of database mining in supporting state-aware query optimization where improved performance is sought by dynamically increasing the utilization of available resources. We consider, in particular, the use of semantic knowledge in enhancing the system performance and the utilization of specialized hardware such as ICL's SCAFS by semantic query reformulation. The idea is to discover semantic information about the data stored in the database using database mining techniques and use it to reformulate queries to make better use of available resources at the time of execution of the query. Thus die execution strategy of the query is based on the current state of the system (and so 'state-aware'). To achieve this we create a rewrite system, consisting of rules and equations mined from the database, mat rewrites queries made to the database for state-aware execution. We provide an architecture for this query pre-processor and discuss performance considerations involved in its implementation.

Audio formatting of a graph

Abstract: The software package of Audio Formatting of a Graph (AFG) is primarily designed for people who are visually challenged to study graph theory. It is menu-driven so that a user can get information about a graph easily and conveniently.

The Grasper-CL

Abstract: Grasper-CL is a system for manipulating and displaying graphs, and for building graph-based user interfaces for application programs. It is implemented in COMMON LISP and CLIM, and has been proven by use in a number of applications. Grasper-CL includes several advances in graph drawing. It contains a graph abstract datatype plus a comprehensive and novel language of operations on that datatype. The appearance of Grasper-CL graphs can be tailored by a wide variety of shape parameters that allow the application to customize the display of nodes and edges for different domains. Default values for shape parameters can be established at several levels. Grasper-CL employs a toolbox approach to graph layout: the system contains a suite of graph layout algorithms that can be applied individually, or in combination to produce hierarchical graph layouts. The system also contains an interactive graph browser.