Integrity Constraints

Relational Data Base Management Systems (RDBMS) are currently the most popular database management systems. The relational model is a simple and powerful model for representing real world applications. However, it lacks the expressiveness of conceptual models. Unlike the latter, the relational model does not offer the generalization abstraction. Therefore, it does not allow the designer to represent directly a large

Object-Role Modeling (ORM) is an approach for modeling and querying information at the conceptual level, and for transforming ORM models and queries to or from other representations. Unlike attribute-based approaches such as Entity-Relationship (ER) modeling and class modeling within the Unified Modeling Language (UML), ORM is fact-oriented, where all facts and rules are modeled in terms of natural sentences easily understood and validated by nontechnical business users. ORM’s modeling procedure facilitates validation by verbalization and population with concrete examples. ORM’s graphical notation is far more expressive than that of ER diagrams or UML class diagrams, and its attribute-free nature makes it more stable and adaptable to changing business requirements. This article explains the fundamentals of ORM, illustrates some of its advantages as a data modeling approach, and outlines some recent research to extend ORM, with special attention to mappings to deductive databases.

Databases are replicated to improve performance and availability. The notion of correctness that has commonly been adopted for concurrent access by transactions to shared, possibly replicated, data is serializability. However, serializability may be impractical in high-performance applications since it imposes too stringent a restriction on concurrency. When serializability is relaxed, the integrity constraints describing the data may be violated. By allowing bounded violations of the integrity constraints, however, we are able to increase the concurrency of transactions that execute in a replicated environment. In this article, we introduce the notion of an N-ignorant transaction, which is a transaction that may be ignorant of the results of at most N prior transactions, which is a transaction that may be ignorant of the results of at most N prior transactions. A system in which all transactions are N-ignorant can have an N + 1-fold increase in concurrency over serializable systems...

Relational Data Base Management Systems (RDBMS) are currently the most popular database management systems. The relational model is a simple and powerful model for representing real world applications. However, it lacks the expressiveness of conceptual models. Unlike the latter, the relational model does not offer the generalization abstraction. Therefore, it does not allow the designer to represent directly a large

En la práctica los esquemas Entidad Interrelación (ER) generados durante la modelación conceptual no son capaces de especificar reglas necesarias para garantizar la integridad de un sistema de información (SI). Aunque han existido intentos, la comunidad de diseñadores de BDs no ha adoptado una práctica para el diseño de la integridad de un SI dado un esquema ER del universo de discurso (UoD). Por tanto es necesario seleccionar un lenguaje con gran nivel de captación semántica para especificar restricciones. Para ello se eligió el lenguaje natural controlado RuleSpeak, unido al Semantic of Business Vocabulary and Rules (SBVR). Finalmente, se muestra la especificación de aquellas restricciones de integridad (RI) definidas por el modelador e impuestas por un agente autorizado del UoD.

Consistent query answering is an inconsistency tolerant approach to obtaining semantically correct answers from a database that may be inconsistent with respect to its integrity constraints. In this work we formalize the notion of consistent query answer for spatial databases and spatial semantic integrity constraints. In order to do this, we first characterize conflicting spatial data, and next, we define admissible instances that restore consistency while staying close to the original instance. In this way we obtain a repair semantics, which is used as an instrumental concept to define and possibly derive consistent query answers. We then concentrate on a class of spatial denial constraints and spatial queries for which there exists an efficient strategy to compute consistent query answers. This study applies inconsistency tolerance in spatial databases, rising research issues that shift the goal from the consistency of a spatial database to the consistency of query answering.

In this paper, we develop a large-scale integer programming model to optimize decision rules for accepting reservations for groups' stays--as well as individuals--in a hotel environment. The proposed model is based on deterministic and randomized mathematical programming methods. Reviewing the literature revealed that, in group reservations models, it was always assumed that the guest arrivals follow a certain distribution. On the contrary, this paper introduces an optimization model that addresses groups' reservations based on ...

ODB-Tools is a integrated environment for the object oriented database (OODB) validation, preserving taxonomy coherence and performing taxonomic inferences, and semantic query optimization. Semantic query optimization uses problem-specific knowledge (e.g. integrity constraints) for transforming a query into an equivalent one (i.e. with the same answer set) that may be answered more efficiently. The approach of the tool is based on two fundamental ingredients. The first one is the OCDL description logics proposed as a common formalism to express class descriptions, a relevant set of integrity constraints rules (IC rules) and queries. The second one are Description Logics inference techniques, exploited to evaluate the logical implications expressed by IC rules and thus to produce the semantic expansion of a given query. The optimizer tentatively applies all the possible transformations and delays the choice of beneficial transformation till the end. ODB-Tools is a ODMG 93 [1] compliant tool, both for the schema definition (ODL language) and for the query language (OQL), The tool is available in internet at http://sparc20.dsi.unimo.it and supports an on-line graphical interface developed in Java language.

Abstract-In addition to data, database systems store various on keys, integrity constraints, class hierarchies), are often kinds of information about their data. Examples are class hierarchies, to define the various data classes and their relationships; integrity constraints, to state required relationships among the data; and inference rules, to define new classes in terms of known classes. This information is often referred to as intensional assumed as well, but little else is assumed. Notable examples of this approach are the various attempts to provide user interfaces to relational databases that achieve logical data independence; i.e., interpret queries that specify information (the data are referred to as extensional information). only a list of attributes and a condition, without naming the Recently, there have been several independent research works that suggested ways by which intensional information may be used to improve the conventional (extensional) database answers. Al...

When updating a knowledge base, several problems may arise. One of the most important problems is that of integrity constraints satisfaction. The classic approach to this problem has been to develop methods forchecking whether a given update violates an integrity constraint. An alternative approach consists of trying to repair integrity constraints violations by performing additional updates thatmaintain knowledge base consistency. Another major problem in knowledge base updating is that ofview updating, which determines how an update request should be translated into an update of the underlying base facts. We propose a new method for updating knowledge bases while maintaining their consistency. Our method can be used for both integrity constraints maintenance and view updating. It can also be combined with any integrity checking method for view updating and integrity checking. The kind of updates handled by our method are: updates of base facts, view updates, updates of deductive rules, and updates of integrity constraints. Our method is based on events and transition rules, which explicity define the insertions and deletions induced by a knowledge base update. Using these rules, an extension of the SLDNF procedure allows us to obtain all possible minimal ways of updating a knowledge base without violating any integrity constraint.

En la práctica los esquemas Entidad Interrelación generados durante la modelación conceptual no son capaces de especificar  restricciones,  necesarias para garantizar la integridad de un sistema de infomación. Aunque han existido intentos, la comunidad de diseñadores de  bases de datos  no ha adoptado una práctica para el diseño de la integridad de un  sistema de información  dado un esquema  entidad interrelación  del universo de discurso. Por tanto es necesario seleccionar un lenguaje con gran nivel de captación semántica para especificar restricciones. Para ello se  eligió el lenguaje natural controlado RuleSpeak, unido al Semantic of Business Vocabulary and Rules. Finalmente, se muestra la  especificación de aquellas restricciones de integridad definidas por el modelador e impuestas por un agente autorizado del negocio.Palabras clave: lenguaje natural, restricciones de integridad, RuleSpeak, SBVR, sistemas de información.

The objective of this paper is to present an approach for target tracking, which incorporates the advanced conce pt of generalized data (kinematics and attribute) association t o improve track maintenance performance in complicated situations ( closely spaced targets), when kinematics data are insufficient for c orrect decision making. It uses Global Nearest Neighbour-like app roach and Munkres algorithm to