Mappings for the Semantic Web

Mappings usually relate two similar knowledge aware resources. Mapping examples abound in thesauri, databases, and ontologies. Additionally, mapping systems can relate two different knowledge resources, such as databases and ontologies. All these mappings are operationally different and are sometimes named differently— for example, correspondences, semantic bridges, transformations, semantic relations, functions, conversions, and domain-method relation

Semantic mappings: out of ontology world limits

Mappings usually relate two similar knowledge representations. Thus, we can find many examples of mappings amid thesauri, databases, ontologies (domain ontologies, top-level and domain ontologies, PSM (Problem Solving Method) and domain ontologies, linguistic and domain ontologies); additionally, we can frequently find systems with mappings that relate two different knowledge representations, for instance, databases and ontologies. All these mappings are operationally different ,and are also named differently (mappings, correspondences, semantic bridges, transformations, semantic relations, functions, conversions, domain-PSM relations), but is there a single definition for these concepts? Can we find common characteristics? This paper analyzes the existing definitions and representation of the term “mapping” (and related terms) in the ontology world and its semantic neighborhood and proposes a new definition and representation of “mapping” for the Semantic Web field

Toll-managed lanes: A simplified benefit-cost analysis of seven US projects

Toll managed lanes are expressway lanes where tolls are used—often in combination with preferred access for high occupancy vehicles and other special traffic management techniques—to improve the highway's capacity, speed or reliability. Such lanes have become popular with transportation policymakers as a way of maintaining free-flowing traffic on certain sections of the highway while also, in some cases, financing the construction of new lanes in congested urban areas. This study examines whether toll-managed lanes are as beneficial as they are popular. The heart of the analysis is the application of a simplified social benefit-cost analysis (BCA) to seven projects. In brief, our results paint a complicated picture of toll-managed lane efficacy. Only two of the seven projects have benefit-cost (B/C) ratios above 1.0 using our base case assumptions about the value of travel time saved and the discount rate, although three others approach or exceed 1.0 with more optimistic but plausible assumptions. The most successful generate not only a significant savings of around 4–5 min per trip for motorists who switch to the managed lane but also smaller per-trip savings for the large majority of motorists who continue to use the general-purpose lanes. It is important to acknowledge, however, that these calculations depend upon some uncertain assumptions about the value of travel time savings and improved reliability

Descubrimiento automático de mappings en un caso de uso real con altas exigencias de certeza

Los sistemas de integración de información resuelven las diferencias entre las fuentes, en la mayoría de los casos, mediante la creación de mappings, puentes semánticos entre los elementos de las fuentes. Hasta ahora se han propuesto comparadores para generar un conjunto de mappings para cada par de elementos de las fuentes a integrar, y se han realizado estudios experimentales con ellos. El valor añadido del presente trabajo frente a los trabajos experimentales anteriores es que se ha llevado a cabo en un caso real embebido en una aplicación real (en el dominio geográfico) con altas exigencias de certeza

OEGMerge: a case-based model for merging ontologies

No long ago ontology merging was a necessary activity, however, the current methods used in ontology merging present neither detailed cases nor an accurate formalization. For validating these methods, it is convenient to have a case list as complete as possible. In this paper we present the OEGMerge model, developed from the OEG (Ontological Engineering Group at UPM) experience, which describes precisely the merging casuistic and the actions to carry out in each case. In this first approach, the model covers only the taxonomy of concepts, attributes and relations

Estudio y formalización del proceso de mezcla de ontologías

Desde hace tiempo la mezcla de ontolog?as es una actividad necesaria, sin embargo, los actuales m?todos de mezcla de ontolog?as no tienen una casu?stica detallada ni una formalizaci?n precisa. Para la validaci?n de estos m?todos, es conveniente disponer de una casu?stica lo m?s completa posible. Por ello, en este art?culo se presenta el modelo OEGMerge, desarrollado a partir de la experiencia del Grupo de Ingenier?a Ontol?gica (OEG) de la UPM, en el que se describe detallada y formalmente la casu?stica de mezcla y las acciones a realizar en cada caso. En esta primera aproximaci?n s?lo se abarca taxonom?a de conceptos, atributos y relaciones

Algoritmo de agregación de mappings basado en reglas de selección

Los sistemas de integración de información resuelven las diferencias entre las fuentes, en la mayoría de los casos, mediante la creación de mappings, puentes semánticos entre los elementos de las fuentes. Hasta ahora se han propuesto técnicas para generar un conjunto de mappings para cada par de elementos de las fuentes a integrar, sin embargo, hasta la publicación del presente trabajo, no se disponía de un algoritmo de agregación público y general para distintos tipos de fuentes que permitiera sintetizar este conjunto de mappings en uno solo. El enfoque aquí presentado está basado en reglas y ha sido aplicado en la integración de catálogos de mobiliario y en la integración de recursos en el dominio geoespacia

Cold Accretion Disks and Lineless Quasars

The optical-UV continuum of quasars is broadly consistent with the emission from a geometrically thin optically thick accretion disk (AD). The AD produces the ionizing continuum which powers the broad and narrow emission lines. The maximum AD effective temperature is given by Teff=fmax(Mdot/M^2)^1/4, where M is the black hole mass, Mdot the accretion rate, and fmax is set by the black hole spin a_*. For a low enough value of Mdot/M^2 the AD may become too cold to produce ionizing photons. Such an object will form a lineless quasar. This occurs for a local blackbody (BB) AD with a luminosity Lopt=10^46 erg/s for M>3.6E9 Msun, when a_*=0, and for M>1.4E10 Msun, when a_*=0.998. Using the AD based Mdot, derived from M and Lopt, and the reverberation based M, derived from Lopt and the Hbeta FWHM, v, gives Teff \propto Lopt^-0.13v^-1.45. Thus, Teff is mostly set by v. Quasars with a local BB AD become lineless for v> 8,000 km/s, when a_*=0, and for v> 16,000 km/s, when a_*=0.998. Higher values of v are required if the AD is hotter than a local BB. The AD becoming non-ionizing may explain why line emitting quasars with v>10,000 km/s are rare. Weak low ionization lines may still be present if the X-ray continuum is luminous enough, and such objects may form a population of weak emission line quasars (WLQ). If correct, such WLQ should show a steeply falling SED at lambda<1000A. Such an SED was observed by Hryniewicz et al. in SDSS J094533.99+100950.1, a WLQ observed down to 570A, which is well modeled by a rather cold AD SED. UV spectroscopy of z~1-2 quasars is required to eliminate potential intervening Lyman limit absorption by the intergalactic medium (IGM), and to explore if the SEDs of lineless quasars and some additional WLQ are also well fit by a cold AD SED.Comment: Accepted for publication in MNRA

The IGN-E case: Integrating through a hidden ontology

National Geographic Institute of Spain (IGN-E) wanted to integrate its main information sources for building a common vocabulary reference and thus to manage the huge amount of information it held. The main problem of this integration is the great heterogeneity of data sources. The Ontology Engineering Group (OEG) is working with IGN-E to attain this objective in two phases: first, by creating automatically an ontology using the semantics of catalogues sections, and second, by discovering mappings automatically that can relate ontology concepts to database instances. So, these mappings are the instruments to break the syntactic, semantic and granularity heterogeneity gap. We have developed software for building a first ontology version and for discovering automatically mappings using techniques that take into account all types of heterogeneity. The ontology contains a set of extra-attributes which are identified in the building process. The ontology, called PhenomenOntology, will be reviewed by domain experts of IGN-E. The automatic mapping discovery will be also used for discovering new knowledge that will be added to the ontology. For increasing the usability and giving independence to different parts, the processes of each phase will be designed automatically and as upgradeable as possible

Ontologías y Web Semántica 2005. Resumen del taller

En este artículo se resumen los resultados obtenidos en el taller “Ontologías y Web Semántica 2005”, que fue celebrado el día 14 de noviembre de 2005 en Santiago de Compostela, en el contexto de la Conferencia de la Asociación Española para la Inteligencia Artificial (CAEPIA2005)