Finding Entities or Information Using Annotations

User-generated content often provides more information than just textual data, i.e. tags or annotations are added to label data, in discussions users can comment on the data, and links exist not only between pages, but also between users and annotations. In this paper we explore the use of annotations in the form of categories to find entities or information in Wikipedia. Main differences between entity ranking and ad hoc retrieval are the assessment criteria, and the provision of target categories for entity ranking topics. From analyzing the relevance assessment sets we can see that entity ranking results have more focused categories. The provided target category is however not always the most informative category. Furthermore we show that techniques for entity ranking can also be applied to ad hoc topics and automatically assigned target categories are good surrogates for manually assigned categories. Although using category information leads to larger improvements on entity ranking topics, significant improvements can also be achieved on ad hoc topics.