Klink-2: integrating multiple web sources to generate semantic topic networks

The amount of scholarly data available on the web is steadily increasing, enabling different types of analytics which can provide important insights into the research activity. In order to make sense of and explore this large-scale body of knowledge we need an accurate, comprehensive and up-to-date ontology of research topics. Unfortunately, human crafted classifications do not satisfy these criteria, as they evolve too slowly and tend to be too coarse-grained. Current automated methods for generating ontologies of research areas also present a number of limitations, such as: i) they do not consider the rich amount of indirect statistical and semantic relationships, which can help to understand the relation between two topics – e.g., the fact that two research areas are associated with a similar set of venues or technologies; ii) they do not distinguish between different kinds of hierarchical relationships; and iii) they are not able to handle effectively ambiguous topics characterized by a noisy set of relationships. In this paper we present Klink-2, a novel approach which improves on our earlier work on automatic generation of semantic topic networks and addresses the aforementioned limitations by taking advantage of a variety of knowledge sources available on the web. In particular, Klink-2 analyses networks of research entities (including papers, authors, venues, and technologies) to infer three kinds of semantic relationships between topics. It also identifies ambiguous keywords (e.g., “ontology”) and separates them into the appropriate distinct topics – e.g., “ontology/philosophy” vs. “ontology/semantic web”. Our experimental evaluation shows that the ability of Klink-2 to integrate a high number of data sources and to generate topics with accurate contextual meaning yields significant improvements over other algorithms in terms of both precision and recall

Towards Best Practices for Crowdsourcing Ontology Alignment Benchmarks

Ontology alignment systems establish the semantic links between ontologies that enable knowledge from various sources and domains to be used by automated applications in many different ways. Unfortunately, these systems are not perfect. Currently, the results of even the best-performing automated alignment systems need to be manually verified in order to be fully trusted. Ontology alignment researchers have turned to crowdsourcing platforms such as Amazon\u27s Mechanical Turk to accomplish this. However, there has been little systematic analysis of the accuracy of crowdsourcing for alignment verification and the establishment of best practices. In this work, we analyze the impact of the presentation of the context of potential matches and the way in which the question is presented to workers on the accuracy of crowdsourcing for alignment verification. Our overall recommendations are that users interested in high precision are likely to achieve the best results by presenting the definitions of the entity labels and allowing workers to respond with true/false to the question of whether or not an equivalence relationship exists. Conversely, if the alignment researcher is interested in high recall, they are better off presenting workers with a graphical depiction of the entity relationships and a set of options about the type of relation that exists, if any

Crowd-assessing quality in uncertain data linking datasets

The quality of a dataset used for evaluating data linking methods, techniques, and tools depends on the availability of a set of mappings, called reference alignment, that is known to be correct. In particular, it is crucial that mappings effectively represent relations between pairs of entities that are indeed similar due to the fact that they denote the same object. Since the reliability of mappings is decisive in order to perform a fair evaluation of automatic linking methods and tools, we call this property of mappings as mapping fairness. In this article, we propose a crowd-based approach, called Crowd Quality(CQ), for assessing the quality of data linking datasets by measuring the fairness of the mappings in the reference alignment. Moreover, we present a real experiment, where we evaluate two state-of-the-art data linking tools before and after the refinement of the reference alignment based on the CQ approach, in order to present the benefits deriving from the crowd assessment of mapping fairness

Contribution à la construction d’ontologies et à la recherche d’information : application au domaine médical

This work aims at providing efficient access to relevant information among the increasing volume of digital data. Towards this end, we studied the benefit from using ontology to support an information retrieval (IR) system.We first described a methodology for constructing ontologies. Thus, we proposed a mixed method which combines natural language processing techniques for extracting knowledge from text and the reuse of existing semantic resources for the conceptualization step. We have also developed a method for aligning terms in English and French in order to enrich terminologically the resulting ontology. The application of our methodology resulted in a bilingual ontology dedicated to Alzheimer’s disease.We then proposed algorithms for supporting ontology-based semantic IR. Thus, we used concepts from ontology for describing documents automatically and for query reformulation. We were particularly interested in: 1) the extraction of concepts from texts, 2) the disambiguation of terms, 3) the vectorial weighting schema adapted to concepts and 4) query expansion. These algorithms have been used to implement a semantic portal about Alzheimer’s disease. Further, because the content of documents are not always fully available, we exploited incomplete information for identifying the concepts, which are relevant for indexing the whole content of documents. Toward this end, we have proposed two classification methods: the first is based on the k nearest neighbors’ algorithm and the second on the explicit semantic analysis. The two methods have been evaluated on large standard collections of biomedical documents within an international challenge.Ce travail vise à permettre un accès efficace à des informations pertinentes malgré le volume croissant des données disponibles au format électronique. Pour cela, nous avons étudié l’apport d’une ontologie au sein d’un système de recherche d'information (RI).Nous avons tout d’abord décrit une méthodologie de construction d’ontologies. Ainsi, nous avons proposé une méthode mixte combinant des techniques de traitement automatique des langues pour extraire des connaissances à partir de textes et la réutilisation de ressources sémantiques existantes pour l’étape de conceptualisation. Nous avons par ailleurs développé une méthode d’alignement de termes français-anglais pour l’enrichissement terminologique de l’ontologie. L’application de notre méthodologie a permis de créer une ontologie bilingue de la maladie d’Alzheimer.Ensuite, nous avons élaboré des algorithmes pour supporter la RI sémantique guidée par une ontologie. Les concepts issus d’une ontologie ont été utilisés pour décrire automatiquement les documents mais aussi pour reformuler les requêtes. Nous nous sommes intéressés à : 1) l’identification de concepts représentatifs dans des corpus, 2) leur désambiguïsation, 3), leur pondération selon le modèle vectoriel, adapté aux concepts et 4) l’expansion de requêtes. Ces propositions ont permis de mettre en œuvre un portail de RI sémantique dédié à la maladie d’Alzheimer. Par ailleurs, le contenu des documents à indexer n’étant pas toujours accessible dans leur ensemble, nous avons exploité des informations incomplètes pour déterminer les concepts pertinents permettant malgré tout de décrire les documents. Pour cela, nous avons proposé deux méthodes de classification de documents issus d’un large corpus, l’une basée sur l’algorithme des k plus proches voisins et l’autre sur l’analyse sémantique explicite. Ces méthodes ont été évaluées sur de larges collections de documents biomédicaux fournies lors d’un challenge international