Document Type


Date of Award


Degree Name

Doctor of Philosophy in Computing Sciences - (Ph.D.)


Computer Science

First Advisor

Senjuti Basu Roy

Second Advisor

Baruch Schieber

Third Advisor

Ioannis Koutis

Fourth Advisor

Yi Chen

Fifth Advisor

Sihem Amer-Yahia


Ensuring fairness and diversity in search results are two key concerns in compelling search and recommendation applications. This work explicitly studies these two aspects given multiple users' preferences as inputs, in an effort to create a single ranking or top-k result set that satisfies different fairness and diversity criteria. From group fairness standpoint, it adapts demographic parity like group fairness criteria and proposes new models that are suitable for ranking or producing top-k set of results. This dissertation also studies equitable exposure of individual search results in long tail data, a concept related to individual fairness. First, the dissertation focuses on aggregating ranks while achieving proportionate fairness (ensures proportionate representation of every group) for multiple protected groups. Then, the dissertation explores how to minimally modify original users' preferences under plurality voting, aiming to produce top-k result set that satisfies complex fairness constraints. A concept referred to as manipulation by modifications is introduced, which involves making minimal changes to the original user preferences to ensure query satisfaction. This problem is formalized as the margin finding problem. A follow up work studies this problem considering a popular ranked choice voting mechanism, namely, the Instant Run-off Voting or IRV, as the preference aggregation method. From the standpoint of individual fairness, this dissertation studies an exposure concern that top-k set based algorithms exhibit when the underlying data has long tail properties, and designs techniques to make those results equitable. For result diversification, the work studies efficiency opportunities in existing diversification algorithms, and designs a generic access primitive called DivGetBatch() to enable that. The contributions of this dissertation lie in (a) formalizing principal problems and studying them analytically. (b) designing scalable algorithms with theoretical guarantees, and (c) extensive experimental study to evaluate the efficacy and scalability of the designed solutions by comparing them with the state-of-the-art solutions using large-scale datasets.



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