The relative ineffectiveness of information retrieval systems is largely caused by the
inaccuracy with which a query formed by a few keywords models the actual user information …

Despite the recent advances in search quality, the fast increase in the size of the Web
collection has introduced new challenges for Web ranking algorithms. In fact, there are still …

Hundreds of millions of users each day use web search engines to meet their information
needs. Advances in web search effectiveness are therefore perhaps the most significant …

In this thesis we consider users' attempts to express their information needs through queries,
or search requests and try to predict whether those requests will be of high or low quality …

Entity-relationship-structured data is becoming more important on the Web. For example,
large knowledge bases have been automatically constructed by information extraction from …

Although Pseudo-Relevance Feedback (PRF) is a widely used technique for enhancing
average retrieval performance, it may actually hurt performance for around one-third of a …

With the overwhelming volume of information, the task of finding relevant information on a
given topic on the Web is becoming increasingly difficult. Web search engines hence …

Query performance predictors are commonly evaluated by reporting correlation coefficients
to denote how well the methods perform at predicting the retrieval performance of a set of …

Large volumes of data on the web or other sources provide users with a wealth of
information. However, archives are becoming more diverse and the language used in text is …

This paper presents a new approach to query expansion in search engines through the use
of general non-topical terms (NTTs) and domain-specific semi-topical terms (STTs). NTTs …