18. The computer program product of claim 17 wherein the program code for defining the impostor profile for the language L further includes program code for determining a degree of closeness between the language L and the language other than the language L based at least in part on the alternative scores for the documents in the set of training documents.
18. The computer program product of claim 17 wherein the program code for defining the impostor profile for the language L further includes program code for determining a degree of closeness between the language L and the language other than the language L based at least in part on the alternative scores for the documents in the set of training documents. 20. The computer program product of claim 18 wherein program code for defining the impostor profile for the language L provides that the impostor set for the language L includes all languages in the plurality of candidate languages, other than the language L, for which the degree of closeness meets a threshold condition.