Infinitesimal reasoning in information retrieval and trust-based recommendation systems

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dc.contributor.author Chowdhury, Maria
dc.date.accessioned 2010-04-26T21:06:56Z
dc.date.available 2010-04-26T21:06:56Z
dc.date.copyright 2010 en
dc.date.issued 2010-04-26T21:06:56Z
dc.identifier.uri http://hdl.handle.net/1828/2651
dc.description.abstract We propose preferential and trust-based frameworks for Information Retrieval and Recommender Systems, which utilize the power of Hyperreal Numbers. In the first part of our research, we propose a preferential framework for Information Retrieval which enables expressing preference annotations on search keywords and document elements, respectively. Our framework is flexible and allows expressing preferences such as “A is infinitely more preferred than B,” which we capture by using hyperreal numbers. Due to widespread use of XML as a standard for representing documents, we consider XML documents in this research and propose a consistent preferential weighting scheme for nested document elements. We show how to naturally incorporate preferences on search keywords and document elements into an IR ranking process using the well-known TF-IDF (Term Frequency - Inverse Document Frequency) ranking measure. In the second part of our research we propose a novel recommender system which enhances user-based collaborative filtering by using a trust-based social network. Again, we use hyperreal numbers and polynomials for capturing natural preferences in aggregating opinions of trusted users. We use these opinions to “help” users who are similar to an active user to come up with recommendations for items for which they might not have an opinion themselves. We argue that the method we propose reflects better the real life behaviour of the people. Our method is justified by the experimental results; we are the first to break a stated “barrier” of 0.73 for the mean absolute error (MAE) of the predicted ratings. Our results are based on a large, real life dataset from Epinions.com, for which, we also achieve a prediction coverage that is significantly better than that of the state-of-the-art methods. en
dc.language English eng
dc.language.iso en en
dc.rights Available to the World Wide Web en
dc.subject Information Retrieval en
dc.subject Recommendation Systems en
dc.subject Search Engine en
dc.subject Trust-based network en
dc.subject hyperreal numbers en
dc.subject infinitesimal en
dc.subject.lcsh UVic Subject Index::Sciences and Engineering::Applied Sciences::Computer science en
dc.title Infinitesimal reasoning in information retrieval and trust-based recommendation systems en
dc.type Thesis en
dc.contributor.supervisor Thomo, Alex
dc.contributor.supervisor Wadge, W. W.
dc.degree.department Dept. of Computer Science en
dc.degree.level Doctor of Philosophy Ph.D. en
dc.identifier.bibliographicCitation 1. Chowdhury Maria, Thomo Alex, and Wadge William "Preferential infinitesimals for information retrieval", { Reference Book: IFIP International Federation for Information Processing, Volume 296; Artificial Intelligence Applications and Innovations III; Eds. Iliadis, L., Vlahavas, I., Bramer, M.; (Boston: Springer), pp. 113-125. Tuesday, July 14, 2009. 2 .Chowdhury Maria, Thomo Alex, and Wadge William "Trust-based infinitesimals for enhanced collaborative Filtering", 15th International Conference on Management of Data (COMAD'09), 2009. en

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