“…Again, the quantities #(c, c ′ , l, D) and #(c, c ′ , * , D) are counted in a similar way but computed on the whole collection D (i.e., over the union of all the graphs from all the documents in the collection). This graph model is a generalization of the model defined in [21] which corresponds to the special case where only one concept set and one relation set are used. In some special cases, our model corresponds to the standard language model (LM) used in [15,20] where relations are not considered (i.e., documents and queries correspond to multiple bag-of-words model) .…”