An introduction to Graph Data Management

A graph database is a database where the data structures for the schema and/or instances are modeled as a (labeled)(directed) graph or generalizations of it, and where querying is expressed by graph-oriented operations and type constructors. In this article we present the basic notions of graph databases, give an historical overview of its main development, and study the main current systems that implement them

A Visual Language for Web Querying and Reasoning

As XML is increasingly being used to represent information on the Web, query and reasoning languages for such data are needed. This article argues that in contrast to the navigational approach taken in particular by XPath and XQuery, a positional approach as used in the language Xcerpt is better suited for a straightforward visual representation. The constructs of the pattern- and rule-based query language Xcerpt are introduced and it is shown how the visual representation visXcerpt renders these constructs to form a visual query language for XML

DYNAMIC HYPERTEXT SYNTHESIS FOR INFORMATION RETRIEVAL

Hypertext navigation alone is insufficient for efficient Information Retrieval (IR). Previous attempts to combine IR techniques with hypertext have been confined to the pre-authored structure of a document. In this paper we extend computer-science methods to synthesize a tailor-made hypertext document in response to each user's query. The synthesis technique can also be used to automatically create a pre-authored hypertext document according to an author's specifications.Information Systems Working Papers Serie

Queries and computation on the web

AbstractThe paper introduces a model of the Web as an infinite, semistructured set of objects. We reconsider the classical notions of genericity and computability of queries in this new context and relate them to styles of computation prevalent on the Web, based on browsing and searching. We revisit several well-known declarative query languages (first-order logic, Datalog, and Datalog with negation) and consider their computational characteristics in terms of the notions introduced in this paper. In particular, we are interested in languages or fragments thereof which can be implemented by browsing, or by browsing and searching combined. Surprisingly, stratified and well-founded semantics for negation turn out to have basic shortcomings in this context, while inflationary semantics emerges as an appealing alternative

Grafos versionables: un soporte para el manejo de la evolución del esquema de una BDOO y para el manejo de versiones de un hipertexto

Presentamos en el informe los conceptos básicos sobre Bases de Datos Orientadas a Objetos (BDOO), Bases de Datos Orientadas a Objetos para CAD, Hipertextos y Versiones. Describimos el modelo general, desarrollado para soportar el manejo de versiones y motivado por los requerimientos de las áreas antes mencionadas. Presentamos un prototipo que captura las características fundamentales del modelo. Mostramos la generalidad del modelo y planteamos posibles extensiones al prototipo al utilizar grafos versionables como un soporte para: * la evolución del esquema de una BDOO * la evolución del esquema de una BDOO extendido para soportar objetos compuestos * la evolución en el tiempo de un hipertexto Finalmente, extendemos el prototipo y lo especializamos para soportar versiones de hipertextos.Tesis digitalizada en SEDICI gracias a la colaboración de la Biblioteca de la Facultad de Informática.Facultad de Ciencias Exacta

Grafos versionables: un soporte para el manejo de la evolución del esquema de una BDOO y para el manejo de versiones de un hipertexto

Presentamos en el informe los conceptos básicos sobre Bases de Datos Orientadas a Objetos (BDOO), Bases de Datos Orientadas a Objetos para CAD, Hipertextos y Versiones. Describimos el modelo general, desarrollado para soportar el manejo de versiones y motivado por los requerimientos de las áreas antes mencionadas. Presentamos un prototipo que captura las características fundamentales del modelo. Mostramos la generalidad del modelo y planteamos posibles extensiones al prototipo al utilizar grafos versionables como un soporte para: * la evolución del esquema de una BDOO * la evolución del esquema de una BDOO extendido para soportar objetos compuestos * la evolución en el tiempo de un hipertexto Finalmente, extendemos el prototipo y lo especializamos para soportar versiones de hipertextos.Tesis digitalizada en SEDICI gracias a la colaboración de la Biblioteca de la Facultad de Informática.Facultad de Ciencias Exacta

Visually querying object-oriented databases

Bibliography: pages 141-145.As database requirements increase, the ability to construct database queries efficiently becomes more important. The traditional means of querying a database is to write a textual query, such as writing in SQL to query a relational database. Visual query languages are an alternative means of querying a database; a visual query language can embody powerful query abstraction and user feedback techniques, thereby making them potentially easier to use. In this thesis, we develop a visual query system for ODMG-compliant object-oriented databases, called QUIVER. QUIVER has a comprehensive expressive power; apart from supporting data types such as sets, bags, arrays, lists, tuples, objects and relationships, it supports aggregate functions, methods and sub-queries. The language is also consistent, as constructs with similar functionality have similar visual representations. QUIVER uses the DOT layout engine to automatically layout a query; QUIVER queries are easily constructed, as the system does not constrain the spatial arrangement of query items. QUIVER also supports a query library, allowing queries to be saved, retrieved and shared among users. A substantial part of the design has been implemented using the ODMG-compliant database system O₂, and the usability of the interface as well as the query language itself is presented. Visual queries are translated to OQL, the standard query language proposed by the ODMG, and query answers are presented using O₂ Look. During the course of our investigation, we conducted a user evaluation to compare QUIVER and OQL. The results were extremely encouraging in favour of QUIVER

SEPEC conference proceedings: Hypermedia and Information Reconstruction. Aerospace applications and research directions. Addendum

The papers presented at the conference on hypermedia and information reconstruction are compiled. The following subject areas are covered: hypertext, typographic man, and the notion of literacy; a knowledge base browser using hypermedia; Ai GERM - a logic programming front end for GERM; and HEAVENS system for software artifacts