... because the importance of the modifier word in retrieval is subordinate to the relation to its headword, but the headword isnot in many phrases. For example, in the case of the query ‘tropical storms’, ... given to the phrase information com-pared to the word information. In this paper, wepropose to differentiate the value of λ in Eq. 3according to the importance of each phrase byadding multiple ... demonstrating the different behaviors of the one-parameter model and the multi-parameters model. On the figure, the un-dotted lines indicate the variation of averageprecision scores when λ value in...