We show that, in a sufficiently large population satisfying certain statistical regularities, it is often possible to accurately estimate the utilitarian social welfare function, even if we only have very noisy data about individual utility functions and interpersonal utility comparisons. In particular, we show that it is often possible to identify an optimal or close-to-optimal utilitarian soc...

We investigate the parameterized complexity of strategic behaviors in generalized scoring rules. In particular, we prove that the manipulation, control (all the 22 standard types), and bribery problems are fixed-parameter tractable for most of the generalized scoring rules, with respect to the number of candidates. Our results imply that all these strategic voting problems are fixed-parameter t...

Recent surveys have shown that a growing number internet users seek medical help online. Yet, recent research [12] has shown that many commercial search engine still struggle in completely satisfying the information need of users. In this work, we present a study on the use of medical terms for query reformulation. We use synonyms and hypernyms from a large medical ontology to generate alternat...

We study the asymptotic average minimum manipulating coalition size as a characteristic of quality of a voting rule and show its serious drawback. We suggest using the asymptotic average threshold coalition size instead. We prove that, in large electorates, the asymptotic average threshold coalition size is maximised among all scoring rules by the Borda rule when the number m of alternatives is...

The classical multiwinner rules are designed for particular purposes. For example, variants of kBorda are used to find k best competitors in judging contests while the Chamberlin-Courant rule is used to select a diverse set of k products. These rules represent two extremes of the multiwinner world. At times, however, one might need to find an appropriate trade-off between these two extremes. We...

This paper studies the dominance-solvability (by iterated deletion of weakly dominated strategies) of general scoring rule voting games. The scoring rules we study include Plurality rule, Approval voting, Negative Plurality Rule, Borda rule and Relative Utilitarianism. We provide a classification of scoring rule voting games according to whether the sufficient conditions for dominance solvabili...

Democratically choosing a single preference from three or more candidate options is not a straightforward matter. There are many competing ideas on how to aggregate rankings of candidates. However, the Gibbard-Satterthwaite theorem pessimistically concludes that no fair voting system is immune to strategic voting. In our work we analyze the likelihood of strategic voting of several popular voti...

Personalized search has recently attracted increasing attention. This paper focuses on utilizing click-through data to personalize the web search results, from a novel perspective based on subspace projection. Specifically, we represent a user profile as a vector subspace spanned by a basis generated from a word-correlation matrix, which is able to capture the dependencies between words in the ...

The correct detection of welding flaws is important to the successful development of an automated weld inspection system. As a continuation of our previous efforts, this study investigates the performance of multi-layer perceptron (MLP) neural networks and case based reasoning (CBR) individually as well as their combined use. It is found that better performance is attained by all the methods te...