A wide variety of different language modeling and smoothing techniques were proposed in the 80s and 90s, including Good-Turing discounting-first applied to the n-gram smoothing at IBM by Katz (Nádas 1984, Church and Gale 1991)-Witten-Bell discounting (Witten and Bell, 1991) , and varieties of class-based ngram models that used information about word classes.