20. The method of claim 17 , wherein a first fielded query of said set of fielded queries is associated with said input query and with said first inverted index, wherein said first fielded query comprises a first conditioned subset of concept tokens of said plurality of tokens, a second conditioned subset of term tokens of said plurality of tokens, and a third conditioned subset of variable tokens of said plurality of tokens, wherein said first conditioned subset is a subset of a set of concept tokens comprised by an intersection of said input query and said first inverted index, wherein said second conditioned subset is a subset of a set of term tokens comprised by an intersection of said input query and said first inverted index, and wherein said third conditioned subset is a subset of a set of variable tokens comprised by said first inverted index.
20. The method of claim 17 , wherein a first fielded query of said set of fielded queries is associated with said input query and with said first inverted index, wherein said first fielded query comprises a first conditioned subset of concept tokens of said plurality of tokens, a second conditioned subset of term tokens of said plurality of tokens, and a third conditioned subset of variable tokens of said plurality of tokens, wherein said first conditioned subset is a subset of a set of concept tokens comprised by an intersection of said input query and said first inverted index, wherein said second conditioned subset is a subset of a set of term tokens comprised by an intersection of said input query and said first inverted index, and wherein said third conditioned subset is a subset of a set of variable tokens comprised by said first inverted index. 21. The method of claim 20 , wherein said set of conditions require that a first sum of a number of tokens in said first conditioned subset plus a number of tokens in said second conditioned subset plus a number of tokens in said third conditioned subset be no less than a second sum of a number of concept tokens in a first minimum fielded document of said first cluster plus a number of term tokens in a second minimum fielded document of said first cluster plus a number of variable term tokens in a third minimum fielded document of said first cluster, wherein no fielded document of said first cluster contains fewer concept tokens than does said first minimum fielded document, no fielded document of said first cluster contains fewer term tokens than does said second minimum fielded document, and no fielded document of said first cluster contains fewer variable tokens than does said third minimum fielded document, and wherein said first sum be no greater than a total number of tokens in a fourth minimum fielded document, wherein no fielded document of said first cluster contains fewer tokens than does said fourth minimum fielded document.