Catálogo de publicaciones - libros

The problem of integration of rules and ontologies is addressed in a general framework based on the well-founded semantics of normal logic programs and inspired by the ideas of Constraint Logic Programming (CLP). are defined as normal clauses extended with in the bodies. The constraints are formulae in a language of a first order theory defined by a set of axioms. Instances of the framework are obtained by specifying a language of constraints and providing . A hybrid program is a pair where is a finite set of hybrid rules. Thus integration of (non-disjunctive) Datalog with ontologies formalized in a Description Logic is covered as a special case.

The paper defines a declarative semantics of hybrid programs and a formal operational semantics. The latter can be seen as an extension of SLS-resolution and provides a basis for hybrid implementations combining Prolog with constraint solvers. In the restricted case of positive rules, hybrid programs are formulae of FOL. In that case the declarative semantics reduces to the standard notion of logical consequence. The operational semantics is sound and it is complete for a restricted class of hybrid programs.

Reactive Web systems, Web services, and Web-based publish/subscribe systems communicate events as XML messages, and in many cases require composite event detection: it is not sufficient to react to single event messages, but events have to be considered in relation to other events that are received over time.

Emphasizing language design and formal semantics, we describe the rule-based query language XChange for detecting composite events. XChange is designed to completely cover and integrate the four complementary querying dimensions: event data, event composition, temporal relationships, and event accumulation. Semantics are provided as model and fixpoint theories; while this is an established approach for rule languages, it has not been applied for event queries before.

Supporting service discovery by semantic service specifications is currently an important research area. While the approaches for the annotation of individual services are well researched, determining the semantics of compositions of services remains an open research issue.

In this paper, we present an approach to generate the semantics of service compositions from the semantics of the contained services. To do this we assume a formal Workflow net model of the service composition. With an example use case we show how this works in practice.

This essay describes fuzzy CARIN, a knowledge representation language combining fuzzy description logics with Horn rules. Fuzzy CARIN integrates the management of fuzzy logic into the non-recursive CARIN system. It provides a sound and complete algorithm for representing and reasoning about fuzzy extended with non-recursive Horn rules. Such an extension is most useful in realistic applications dealing with uncertainty and imprecision, such as multimedia processing and medical applications. Additionally, it provides the ability of answering to union of conjunctive queries, which is a novelty not previously addressed by fuzzy DL systems.

In the ongoing discussion about combining rules and Ontologies on the Semantic Web a recurring issue is how to combine first-order classical logic with nonmonotonic rule languages. Whereas several modular approaches to define a combined semantics for such hybrid knowledge bases focus mainly on decidability issues, we tackle the matter from a more general point of view. In this paper we show how Quantified Equilibrium Logic (QEL) can function as a unified framework which embraces classical logic as well as disjunctive logic programs under the (open) answer set semantics. In the proposed variant of QEL we relax the unique names assumption, which was present in earlier versions of QEL. Moreover, we show that this framework elegantly captures the existing modular approaches for hybrid knowledge bases in a unified way.

The most promising feature of the Web services platform is its ability to form new (composite) services by combining the capabilities of already existing (component) services. The existing services may themselves be composite leading to a hierarchical composition. In this work, we focus on the discovery aspect. We generalize the characteristics of a service, which need to be considered for successful execution of the service, as constraints. We present a predicate logic model to specify the corresponding constraints. Further, composite services are also published in a registry and available for discovery (hierarchical composition). Towards this end, we show how the constraints of a composite service can be derived from the constraints of its component services in a consistent manner. Finally, we present an incremental matchmaking algorithm which allows bounded inconsistency.

The adequate representation of emotions in affective computing is an important problem and the starting point of studies related to emotions. There are different approaches for representing emotions, selecting one of this existing methods depends on the purpose of the application. Another problem related to emotions is the amount of different emotional concepts which makes it very difficult to find the most specific emotion to be expressed in each situation. This paper presents a system that reasons with an ontology of emotions implemented with semantic web technologies. Each emotional concept is defined in terms of a range of values along the three-dimensional space of emotional dimensions. The capabilities for automated classification and establishing taxonomical relations between concepts are used to provide a bridge between an unrestricted input and a restricted set of concepts for which particular rules are provided. The rules applied at the end of the process provide configuration parameters for a system for emotional voice synthesis.

WSML presents a framework encompassing different language variants, rooted in Description Logics and (F-)Logic Programming. So far, the precise relationships between these variants have not been investigated. We take the nonmonotonic , which generalizes both Description Logics and Logic Programming, and extend it with frames and concrete domains, to capture all features of WSML; we call this novel formalism FF-AEL. We consider two forms of language layering for WSML, namely and layering, where the latter enforces additional restrictions on the use of certain language constructs in the rule-based language variants, in order to give additional guarantees about the layering. Finally, we demonstrate that each WSML variant semantically corresponds to its target formalism, i.e. WSML-DL corresponds to , WSML-Rule to the Stable Model Semantics for Logic Programs (the Well-Founded Semantics can be seen as an approximation), and WSML-Core to (without nominals), a Horn subset of .

Business rules are statements that express (certain parts of) a business policy, defining terms and defining or constraining the operation of an entreprise, in a declarative manner. The business rule approach is more and more used due to the fact that in such systems, business experts can maintain the complex behavior of their application in a “zero development” environment. There exist more and more business rule management systems (BRMS) and rule engines, adding new needs in the business rules community. Currently the main requirement in this domain is having a standard language for representing business rules, facilitating their integration and share. Works for solving this lack are in progress at e.g OMG and W3C.

The aim of this paper is to propose a way to automatically generate a part of the business rules by combining concepts coming from Model Driven Architecture and Semantic Web using the Ontology Definition Metamodel.

Geo-ontologies have a key role to play in the development of the geospatial-semantic web, with regard to facilitating the search for geographical information and resources. They normally hold large amounts of geographic information and undergo a continuous process of revision and update. Hence, means of ensuring their integrity are crucial and needed to allow them to serve their purpose. This paper proposes the use of qualitative spatial reasoning as a tool to support the development of a geo-ontology management system. A new framework for the representation of and reasoning over geo-ontologies is presented using the web ontology language (OWL) and its associated reasoning tools. Spatial reasoning and integrity rules are represented using a spatial rule engine extension to the reasoning tools associated with OWL. The components of the framework are described and the implementation of the spatial reasoning engine is presented. This work is a step towards the realisation of a complete geo-ontology management system for the semantic web.