Showing papers on "Graph database published in 1997"

Adding Structure to Unstructured Data

Abstract: We develop a new schema for unstructured data. Traditional schemas resemble the type systems of programming languages. For unstructured data, however, the underlying type may be much less constrained and hence an alternative way of expressing constraints on the data is needed. Here, we propose that both data and schema be represented as edge-labeled graphs. We develop notions of conformance between a graph database and a graph schema and show that there is a natural and efficiently computable ordering on graph schemas. We then examine certain subclasses of schemas and show that schemas are closed under query applications. Finally, we discuss how they may be used in query decomposition and optimization.

Multi-document summarization by graph search and matching

Abstract: We describe a new method for summarizing similarities and differences in a pair of related documents using a graph representation for text. Concepts denoted by words, phrases, and proper names in the document are represented positionally as nodes in the graph along with edges corresponding to semantic relations between items. Given a perspective in terms of which the pair of documents is to be summarized, the algorithm first uses a spreading activation technique to discover, in each document, nodes semantically related to the topic. The activated graphs of each document are then matched to yield a graph corresponding to similarities and differences between the pair, which is rendered in natural language. An evaluation of these techniques has been carried out.

Building a scaleable geo-spatial DBMS: technology, implementation, and evaluation

Abstract: This paper presents a number of new techniques for parallelizing geo-spatial database systems and discusses their implementation in the Paradise object-relational database system. The effectiveness of these techniques is demonstrated using a variety of complex geo-spatial queries over a 120 GB global geo-spatial data set.

On the complexity of database queries (extended abstract)

Abstract: We revisit the issue of the complexity of database queries, in the light of the recent parametric refinement of complexity theory. We show that, if the query size (or the number of variables in the query) is considered as a parameter, then the relational calculus and its fragments (conjunctive queries, positive queries) are classified at appropriate levels of the so-called W hierarchy of Downey and Fellows. These results strongly suggest that the query size is inherently in the exponent of the data complexity of any query evaluation algorithm, with the implication becoming stronger as the expressibility of the query language increases. For recursive languages (fixpoint logic, Datalog) this is provably the case [14]. On the positive side, we show that this exponential dependence can be avoided for the extension of acyclic queries with # (but not <) inequalities.

Method and apparatus for maintaining multiple representations of a same scene in computer generated graphics

Abstract: A method for creating and maintaining a dual scene graph for the display of a computer generated object. The user creates a user scene graph which has a number of node in a hierarchical organization which represents an object. This user scene graph is organized according to the dictates of the user for ease of human comprehension. The computer system automatically converts this user scene graph into a separate scene graph. The organization of this second scene graph is optimized so that the object can be rendered faster and more efficiently. Thereby, the first scene graph is displayed to the user so that the user can add, delete, or otherwise modify the object. Any changes made to the user scene graph are automatically made to the second scene graph, transparent to the user. The object is rendered for display according to the second scene graph.

Storage management for evolving databases

Abstract: The problem of maintaining data that arrives continuously over time is increasingly prevalent in databases and digital libraries. Building on a model for sliding window indices developed by N. Shivakumar and H. Garcia-Molina (1997), we devise efficient algorithms for some of the central problems that arise. We also show connections between the problems in this model and some fundamental problems in optimization and graph theory.

An analysis of semantic overload in database access systems using multi-table query formulation

Abstract: Theory suggests that semantic overload in database representations and query languages may be a significant contributing factor to difficulties in end-user access to corporate databases. With respect to join queries, two aspects of SQL-based relational database management systems are overloaded: (1) foreign key columns are overloaded to represent both attributes and relationships and (2) the WHERE clause in SQL is overloaded to include both selection criteria and join criteria. We experimentally test the semantic overload theory by comparing end user performance using data access systems (DASs) that address these aspects individually and in combination. Eliminating the overload in foreign key columns by adding an explicit relationship construct to the standard tabular relational database representation significantly improved end user performance. Eliminating the overload in the SQL WHERE clause by adding an explicit join construct, similar to that included in SQL2, reduced certain types of errors but did not significantly improve performance. We conclude that for organizations seeking to improve end user performance in multi-table database queries it is more effective simply to use an explicit relationship representation in documenting the database structure than to invest in a database query language, such as SQL2, that has an explicit join syntax.

Database: Models, Languages, Design

Abstract: I DATABASE MODELS AND ACCESS METHODS 1. Introduction to Databases 2. Relational Databases 3. Relational Algebra 4. Relational Calculus 5. Basic SQL 6. Advanced SQL 7. Object-Oriented Databases 8. Object-Oriented Queries 9. Deductive Databases 10. Deductive Queries 11. Network Databases 12. Hierarchical Databases 13. Comparing the Database Models II DISK STORAGE MANAGEMENT 14. File Structures 15. Indexes 16. File Structures for the Database Models III DATABASE DESIGN 17. Application Design Capture 18. Functional Dependency Analysis 19. Join Dependency Analysis IV EPILOGUE 20. Performance

A Structure-Based Approach to Querying Semi-Structured Data

Abstract: Several researchers have considered integrating multiple unstructured, semi-structured, and structured data sources by modeling all sources as edge labeled graphs. Data in this model is self-describing and dynamically typed, and captures both schema and data information. The labels are arbitrary atomic values, such as strings, integers, reals, etc., and the integrated data graph is stored in a unique data repository, as a relation of edges. The relation is dynamically typed, i.e. each edge label is tagged with its type.

On the Containment and Equivalence of Database Queries with Linear Constraints.

Abstract: We develop a new technique based on counter machines to study the containment and equivalence of queries with linear constraints overintegers Z, natural numbers M, rational numbers Q and real numbers R We show that the problems are decidable in double exponential time with an exponential time lower bound for conjunctive queries with linear constraints over Z and lV, decidable in double exponential time for constant-free conjunctive queries with linear constraints over Q and R. For the general classes of conjunctive queries with linear constraints over Q and R, the problems are decidable in double exponential space using reductions to the first-order theory of reals with addition. We also use the counter machine technique to show that for “connected” first-order queries with linear constraints over Z and lV, the containment and equivalence problems are decidable over “bounded-degree databases”.

Software synthesis for dynamic data flow graph

Abstract: Data flow graph is a useful computational model to describe the functionality of a digital system. To execute a data flow graph on a target system, it should be synthesized to the code to be compiled on the target system. Current research activities on software synthesis are mainly focused on Synchronous Data Flow (SDF) graph, which can not represent the control structure of the application. On the other hand, Dynamic Data Flow (DDF) graph can express the control structure, such as conditionals and data dependent iterations. This paper synthesizes a C code for a DDF graph which includes not only the functions associated with the nodes of the graph, but also the run-time scheduler and the run-time buffer manager which can execute a DDF graph without deadlock with bounded memory requirement. In addition, this paper suggests hierarchical implementation of DDF which enhances the efficiency of run-time scheduling by clustering SDF type nodes as a specific macro node.

Flexible Database Querying Based on Associations of Domain Values

Abstract: In this paper we present an approach to database querying based on fuzzy evaluation of queries. In the approach a dedicated mining for domain knowledge is involved. The result of this is a special kind of associations between values and is represented in fuzzy networks. Such a network is used to relax queries and to relate objects in the database. The network exploit the database, in the sense that it is obtained by pure statistical means from mining the database for associations between domain values. It is a special variant of a projection of, or a orthogonal view on, data in the database.

An automatic visual database interface

Abstract: Today’s relational and object-oriented databases come with very powerful declarative query languages like SQL. However, such languages are still not adapted to the needs of the occasional user because of their syntax requirements and because they do not facilitate the understanding of the database semantics, navigation within tables and the formulation of queries.

Databases for criminal intelligence analysis: knowledge representation issues

Abstract: Criminal intelligence data poses problems for conventional database technology. It has little structure or homogeneity and queries may involve looking for unknown associations between entities; such open-ended queries cannot be made in current systems. Finally, the data must be presented in an intuitively simple fashion for both investigative and evidential purposes. We discuss a database system which uses a labelled graph as its data model. This approach obviates the need for schema design, allows queries which look for associations between entities to be implemented and provides the basis for a natural visual representation of the data.

Method for recognizing table based on graph

Abstract: PROBLEM TO BE SOLVED: To provide a method for recognizing a table in document by composing this method of various steps for operating the text entity of graph with label while using at least one rewrite rule so as to discriminates the structure of the document SOLUTION: First of all, in a segmentation process 40, a segmentation subsystem discriminate the text and the document part of an image Next, a graph preparation process 50 prepares the layout graph of the document while using segmentated parts Afterwards, in an entity recognition process 60, an entity recognition subsystem adds a tag having the label from the alphabet of a document node to each text part Finally, in a graph rewrite process 70, a graph rewrite sub-system processes the entity of graph with the label and discriminates a composed document 85 COPYRIGHT: (C)1997,JPO

Constructing memorable asymmetric information diagrams in three dimensions

Abstract: This paper presents a model for presenting relational information as a graph in three dimensions, where the emphasis is on the location of nodes by recognition of their locality in the drawing rather than the tracing of paths through the graph. The approach exploits the potential of 3D to present graphs with a high number of nodes specific to an individual user, such as a graph of web-page bookmarks. The key element is the creation of a memorable structure that contains a variety of sub-structures which act as reference points for the viewer as they manipulate their own viewpoint within the three dimensional virtual space of the graph layout. The layout algorithm used here challenges the need for an aesthetic of symmetry in graph drawing within 3D and exploits the user’s ability to recall sub-structures within a drawing to replace edge-tracing as the means for locating nodes in the drawing.

An approach towards parallelisation of sequential programs in an interactive environment

Abstract: This paper presents an approach for extraction of functional parallelism from sequential programs in an interactive environment. It uses Hierarchical Task Graph (HTG) as an intermediate representation of a parallel program. This graph is constructed starting from the entire sequential program as its root node, considering both loop nodes and conditional nodes as its intermediate nodes and the basic blocks as the leaf nodes. During an interactive session, the user can move across different levels of the HTG and may test whether different nodes can be executed in parallel. The user can even cross the basic block boundary to increase the scope of parallelisation. Once the Control Flow Graph for parallel code generation is decided through such interaction, the Execution Conditions for the nodes of this graph are derived using an efficient method.

Object-oriented evolutionary database design for software metrics data

Abstract: The authors present an approach to manage evolutionary changes that take place over time in an object-oriented software metrics database schema. The framework is based on the entity-relation (E-R) model and uses a recursive graph structure, known as R-graph, to support the views of software quality and risk. The fundamental mechanism for abstracting views is the introduction of two semantic operators for the R-graph. These operators are proposed based on graph-based predicates and Petri-net based predicate formalism for view abstraction.

Techniques for multiple database integration

Abstract: : There are several graphic client/server application development tools which can be used to easily develop powerful relational database applications However, they do not provide a direct means of performing queries which require relational joins across multiple database boundaries This thesis studies ways to access multiple databases Specifically, it examines how a 'cross-database join' can be performed A case study of techniques used to perform joins between academic department financial management system and course management system databases was done using PowerBuilder 50 Although we were able to perform joins across database boundaries, we found that PowerBuilder is not conducive to cross-database join access because no relational database engine is available to execute cross-database queries