19. The method of claim 18, wherein steps (a) to (d) are repeated until only unclassified putative 1-grams are left.
18. In a computer based language modelling system receiving data in the form of a series of n-grams, each n-gram comprising a series of "n" words (w.sub.1, w.sub.2, . . . , w.sub.n), each n-gram having an associated count, a method of classifying the n-grams into non-redundant classes, the method comprising the steps of: (a) comparing the count of each n-gram to a first threshold value and classifying each n-gram with a count greater than said first threshold in a first class; (b) associating all n-grams not classified in step (a) with a putative (n-1)-gram class, each said putative (n-1)-gram class having the same last "n-1" words (w.sub.2, w.sub.3, . . . , w.sub.n); (c) summing the counts of each n-gram in said putative (n-1)-gram class to establish a complement count for each said putative (n-1)-gram class; and (d) comparing said complement count of each said putative (n-1)-gram class to a second threshold value and classifying each said putative (n-1)-gram class with a count greater than said second threshold in a second class.