Semantic Information Retrieval: current situation

This article focuses on the field of Semantic Information Retrieval (IR), which is at the intersection of several disciplines: Information Retrieval, Knowledge Engineering and Natural Language Processing. We present the basics to understand how a semantic IR system works. We also present a classification of the types of semantic resources used in information retrieval. We detail the role of the documents' annotation phase using a resource and the processing of these annotations in the indexing space. We detail the three main types of information retrieval models and how the new indexing space is exploited.