Master Thesis Defense: Umut Öztok
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  • Master Thesis Defense: Umut Öztok

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GENERATING EXPLANATIONS FOR COMPLEX BIOMEDICAL QUERIES

 

Umut Öztok

Computer Science and Engineering, MS Thesis, 2012 

Thesis Jury

Asst. Prof. Esra Erdem (Thesis Supervisor), Assoc. Prof. Hans Tompits, Asst. Prof. Hüsnü Yenigün, Assoc. Prof. Uğur Osman Sezerman, Asst. Prof. Volkan Patoğlu 

Date &Time: August 7th, 2012 - 15:40

Place: FENS L063

Abstract

Recent advances in health and life sciences have led to generation of a large amount of biomedical data. To facilitate access to its desired parts, such a big mass of data has been represented in structured forms, like databases and ontologies. On the other hand, representing these databases and ontologies in different formats, constructing them independently from each other, and storing them at different locations have brought about many challenges for answering queries about the knowledge represented  in these ontologies and databases.

One of the challenges for the users is to be able to represent such a biomedical query in a natural language, and get its answers in an understandable form. Another challenge is to extract relevant knowledge from different knowledge resources, and integrate them appropriately using also definitions, such as, chains of gene-gene interactions, cliques of genes based on gene-gene relations, or similarity/diversity of genes/drugs. Furthermore, once an answer is found for a complex query, the experts may need further explanations about the answer. The first two challenges have been addressed earlier using Answer Set Programming (ASP),with the  development of a software system (called BioQuery-ASP). This thesis addresses the third challenge: explanation generation in ASP.

In this thesis, we extend the earlier work on the first two challenges, to new forms of biomedical queries  (e.g., about drug similarity) and to new biomedical knowledge resources. We introduce novel mathematical models and algorithms to generate (shortest or k different) explanations for queries in ASP, and provide a comprehensive theoretical analysis of these methods. We implement these algorithms and integrate them in BioQuery-ASP, and provide an experimental evaluation of our methods with some complex biomedical queries over the biomedical knowledge resources PHARMGKB, DRUGBANK, BIOGRID, CTD, SIDER, DISEASE ONTOLOGY, and ORPHADATA.