A class of structures is said to have the homomorphism-preservation property just in case every firstorder formula that is preserved by homomorphisms on this class is equivalent to an existential-positive formula. It is known by a result of Rossman that the class of finite structures has this property and by previous work of Atserias et al. that various of its subclasses do. We extend the latte...

In our TREC participation, we used an ensemble approach in query expansion. Query expansion, such as synonym expansion, had shown promising results in medical literature search. On the other hand, some of the 2011 papers reported worse results from expansion. Since there are multiple knowledge sources available and each resource has clear strengths and weaknesses, we tested the combination of t...

The research reported in this paper has both a scientific and a commercial aim. The scientific interest is to explore the use of contexts in order to improve the quality of information brokering. In this paper it is shown that contexts in information brokering can be exploited to enable four directions of query reformulation: up and down (standard query expansion) and sideway reformulations of ...

The CDS track investigates methods that could help physicians find relevant medical cases for patients they are dealing with. Concept based representation has been shown to be effective in biomedical domain. However, the basic concept based retrieval method may not perform well because of the additional restriction on each clinical cases. Therefore, in this paper, we explored two external resou...

Given integers s and t, define a function φs,t on the space of all formal complex series expansions by φs,t( P

RÉSUMÉ. La tâche de notre recherche est de fournir le contexte de recherche à un moteur de recherche, i.e. étendre une requête. Nous proposons une méthode d’expansion automatique de requêtes basée sur la proximité des termes. Elle estime l’importance des termes candidats selon la proximité des termes de la requête dans les premiers documents retrouvés. L’évaluation sur les collections TREC indi...

An overview is given to a new approach for obtaining generalized Fourier transforms in the context of hypercomplex analysis (or Clifford analysis). These transforms are applicable to higher-dimensional signals with several components and are different from the classical Fourier transform in that they mix the components of the signal. Subsequently, attention is focused on the special case of the...

In this paper, we present our participation in the Medical Records Track of TREC 2012. This is the second time we take part in this track. 50 new topics have been published in this year. The goal of this track is still to find relevant patients that have particular diseases and/or treatments. To achieve this goal, we try four methods which include popular techniques like query expansion, concep...