Answer type validation in question answering systems

In open domain question-answering systems, numerous questions wait for answers of an explicit type. For example, the question "Which president succeeded Jacques Chirac?" requires an instance of president as answer. The method we present in this article aims at verifying that an answer given by a system corresponds to the given type. This verification is done by combining criteria provided by different methods dedicated to verify the appropriateness between an answer and a type. The first types of criteria are statistical and compute the presence rate of both the answer and the type in documents, other criteria rely on named entity recognizers and the last criteria are based on the use of Wikipedia.