thesis cover image of a smart computer

Combining Concepts and Language Models for Information Access

Since the middle of last century, information retrieval has gained an increasing interest. Since its inception, much research has been devoted to finding optimal ways of representing both documents and queries, as well as improving ways of matching one with the other. In cases where document annotations or explicit semantics are available, matching algorithms can be informed using the concept languages in which such semantics are usually defined. These algorithms are able to match queries and documents based on textual and semantic evidence.

Recent advances have enabled the use of rich query representations in the form of query language models. This, in turn, allows us to account for the language associated with concepts within the retrieval model in a principled and transparent manner. Developments in the semantic web community, such as the Linked Open Data cloud, have enabled the association of texts with concepts on a large scale. Taken together, these developments facilitate a move beyond manually assigned concepts in domain-specific contexts into the general domain.

This thesis investigates how one can improve information access by employing the actual use of concepts as measured by the language that people use when they discuss them. The main contribution is a set of models and methods that enable users to retrieve and access information on a conceptual level. Through extensive evaluations, a systematic exploration and thorough analysis of the experimental results of the proposed models is performed. Our empirical results show that a combination of top-down conceptual information and bottom-up statistical information obtains optimal performance on a variety of tasks and test collections.

See http://phdthes.is/ for more information.

  • [PDF] E. Meij, “Combining concepts and language models for information access,” PhD Thesis, 2010.
    [Bibtex]
    @phdthesis{2010:meij,
    Author = {Meij, Edgar},
    Date-Added = {2011-10-20 10:18:00 +0200},
    Date-Modified = {2011-10-22 12:23:33 +0200},
    School = {University of Amsterdam},
    Title = {Combining Concepts and Language Models for Information Access},
    Year = {2010}}

 

My first BioAID: heuristic support for hypothesis construction from literature

Motivation

Constructing a new hypothesis is often the first step for a new cycle of experiments. A typical approach to harvesting biological literature is to scan the results of a PubMed query and read what we think is most relevant. In this scenario, we are limited by the selection of papers and, for future applications, we are limited by our capacity to recall the knowledge we have gained. As part of the development of a ‘virtual laboratory for bioinformatics,’ we seek alternative ways to support the construction of hypotheses from biological literature.

Objectives

Our objective is to provide automated support for hypothesis formation from literature based on an initial seed of knowledge.

Approach

Our approach consists of the following steps: first we create a ‘proto-ontology’ from the knowledge that we want to extend, for instance, a table in a review that lists diseases associated with a particular enzyme. We then identify the collection of documents that we want to search (typically Medline). Subsequently, we use concepts from our proto-ontology as input to retrieve relevant documents from a collection and to inform us of concepts such as protein names or relationships that are putatively associated with the proto- ontology. These results are used to enrich the proto-ontology with additional concepts and relations. The ontology can be iteratively enriched by using the results from one run as input for the next.

Implementation

Our implementation is based on a collection of web services, allowing us to construct custom workflows for specific tasks. Together, these web services form a toolbox called AIDA (Adaptive Information Disclosure Application), for annotating documents, searching documents, discovering knowledge from documents, and storing ontological data. AIDA uses open source software such as Lucene for document retrieval, and Sesame for handling ontologies. For the purposes of this implementation, we have also used Taverna to construct our workflows and Protégé.

Results

We have created workflows from services in the AIDA toolbox, and applied them to extend a proto- ontology with knowledge extracted from literature. Technically, the most challenging workflow uses our own proto-ontology as input for machine learning services, after which biological concepts are discovered that are related to terms from our own ontology. As a proof of concept, we have (re)discovered diseases that are known to be related to EZH2, an enzyme associated with gene regulation via chromatin remodelling. A second workflow which discovers genomics concepts is used to identify proteins that might present a previously unreported link between two biological concepts, e.g. histones and transcription factors. The proto-ontology and enriched ontology are written in the Web Ontology Language OWL, and stored in Sesame via another service from the toolbox.

Availability

Services and workflows are available from http://ws.adaptivedisclosure.org/BioAIDdemo1. Ontologies are available from http://rdf.adaptivedisclosure.org/BioAIDdemo1.

Conclusion

Workflows constructed from the AIDA toolbox can be used as an aid in constructing hypotheses from literature. We show that we can automatically extend a proto-ontology with new hypothetical concepts and relationships that bridge across the boundaries of single papers or biological subdomains. Our approach can be customized to particular domains and vocabularies through the choice of ontology and literature corpora.

  • [PDF] M. Roos, S. Katrenko, W. R. van Hage, E. Meij, M. S. Marshall, and P. W. Adriaans, “My first bioaid: heuristic support for hypothesis construction,” in Ismb-eccb’07, 2007.
    [Bibtex]
    @inproceedings{ISMB:2007:Roos,
    Author = {Roos, M. and Katrenko, S. and van Hage, W.R. and Meij, E. and Marshall, M.S. and Adriaans, P.W.},
    Booktitle = {ISMB-ECCB'07},
    Date-Added = {2011-10-13 08:56:20 +0200},
    Date-Modified = {2011-10-13 08:56:20 +0200},
    Title = {My first BioAID: heuristic support for hypothesis construction},
    Year = {2007}}