Query-Driven On-The-Fly Knowledge Base Construction

Today's openly available knowledge bases, such as DBpedia, Yago, Wikidata or Freebase, capture billions of facts about the world's entities. However, even the largest among these (i) are still limited in up-to-date coverage of what happens in the real world, and (ii) miss out on many relevant predicates that precisely capture the wide variety of relationships among entities. To overcome both of these limitations, we propose a novel approach to build on-the-fly knowledge bases in a query-driven manner. Our system, called QKBfly, supports analysts and journalists as well as question answering on emerging topics, by dynamically acquiring relevant facts as timely and comprehensively as possible. QKBfly is based on a semantic-graph representation of sentences, by which we perform three key IE tasks, namely named-entity disambiguation, co-reference resolution and relation extraction , in a light-weight and integrated manner. In contrast to Open IE, our output is canonicalized. In contrast to traditional IE, we capture more predicates, including ternary and higher-arity ones. Our experiments demonstrate that QKBfly can build high-quality, on-the-fly knowledge bases that can readily be deployed, e.g., for the task of ad-hoc question answering. </jats:p

A New Approach to Information Extraction in User-Centric E-Recruitment Systems

In modern society, people are heavily reliant on information available online through various channels, such as websites, social media, and web portals. Examples include searching for product prices, news, weather, and jobs. This paper focuses on an area of information extraction in e-recruitment, or job searching, which is increasingly used by a large population of users in across the world. Given the enormous volume of information related to job descriptions and users’ profiles, it is complicated to appropriately match a user’s profile with a job description, and vice versa. Existing information extraction techniques are unable to extract contextual entities. Thus, they fall short of extracting domain-specific information entities and consequently affect the matching of the user profile with the job description. The work presented in this paper aims to extract entities from job descriptions using a domain-specific dictionary. The extracted information entities are enriched with knowledge using Linked Open Data. Furthermore, job context information is expanded using a job description domain ontology based on the contextual and knowledge information. The proposed approach appropriately matches users’ profiles/queries and job descriptions. The proposed approach is tested using various experiments on data from real life jobs’ portals. The results show that the proposed approach enriches extracted data from job descriptions, and can help users to find more relevant jobs

Joint models for information and knowledge extraction

Information and knowledge extraction from natural language text is a key asset for question answering, semantic search, automatic summarization, and other machine reading applications. There are many sub-tasks involved such as named entity recognition, named entity disambiguation, co-reference resolution, relation extraction, event detection, discourse parsing, and others. Solving these tasks is challenging as natural language text is unstructured, noisy, and ambiguous. Key challenges, which focus on identifying and linking named entities, as well as discovering relations between them, include: • High NERD Quality. Named entity recognition and disambiguation, NERD for short, are preformed first in the extraction pipeline. Their results may affect other downstream tasks. • Coverage vs. Quality of Relation Extraction. Model-based information extraction methods achieve high extraction quality at low coverage, whereas open information extraction methods capture relational phrases between entities. However, the latter degrades in quality by non-canonicalized and noisy output. These limitations need to be overcome. • On-the-fly Knowledge Acquisition. Real-world applications such as question answering, monitoring content streams, etc. demand on-the-fly knowledge acquisition. Building such an end-to-end system is challenging because it requires high throughput, high extraction quality, and high coverage. This dissertation addresses the above challenges, developing new methods to advance the state of the art. The first contribution is a robust model for joint inference between entity recognition and disambiguation. The second contribution is a novel model for relation extraction and entity disambiguation on Wikipediastyle text. The third contribution is an end-to-end system for constructing querydriven, on-the-fly knowledge bases.Informations- und Wissensextraktion aus natürlichsprachlichen Texten sind Schlüsselthemen vieler wissensbassierter Anwendungen. Darunter fallen zum Beispiel Frage-Antwort-Systeme, semantische Suchmaschinen, oder Applikationen zur automatischen Zusammenfassung und zum maschinellem Lesen von Texten. Zur Lösung dieser Aufgaben müssen u.a. Teilaufgaben, wie die Erkennung und Disambiguierung benannter Entitäten, Koreferenzresolution, Relationsextraktion, Ereigniserkennung, oder Diskursparsen, durchgeführt werden. Solche Aufgaben stellen eine Herausforderung dar, da Texte natürlicher Sprache in der Regel unstrukturiert, verrauscht und mehrdeutig sind. Folgende zentrale Herausforderungen adressieren sowohl die Identifizierung und das Verknüpfen benannter Entitäten als auch das Erkennen von Beziehungen zwischen diesen Entitäten: • Hohe NERD Qualität. Die Erkennung und Disambiguierung benannter Entitäten (engl. "Named Entity Recognition and Disambiguation", kurz "NERD") wird in Extraktionspipelines in der Regel zuerst ausgeführt. Die Ergebnisse beeinflussen andere nachgelagerte Aufgaben. • Abdeckung und Qualität der Relationsextraktion. Modellbasierte Informationsextraktionsmethoden erzielen eine hohe Extraktionsqualität, bei allerdings niedriger Abdeckung. Offene Informationsextraktionsmethoden erfassen relationale Phrasen zwischen Entitäten. Allerdings leiden diese Methoden an niedriger Qualität durch mehrdeutige Entitäten und verrauschte Ausgaben. Diese Einschränkungen müssen überwunden werden. • On-the-Fly Wissensakquisition. Reale Anwendungen wie Frage-Antwort- Systeme, die Überwachung von Inhaltsströmen usw. erfordern On-the-Fly Wissensakquise. Die Entwicklung solcher ganzheitlichen Systeme stellt eine hohe Herausforderung dar, da ein hoher Durchsatz, eine hohe Extraktionsqualität sowie eine hohe Abdeckung erforderlich sind. Diese Arbeit adressiert diese Probleme und stellt neue Methoden vor, um den aktuellen Stand der Forschung zu erweitern. Diese sind: • Ein robustesModell zur integrierten Inferenz zur gemeinschaftlichen Erkennung und Disambiguierung von Entitäten. • Ein neues Modell zur Relationsextraktion und Disambiguierung von Wikipedia-ähnlichen Texten. • Ein ganzheitliches System zur Erstellung Anfrage-getriebener On-the-Fly Wissensbanken