The shrinking methods must take into account all the transitions sharing the same input label at the state identified with h and its backoff state h .
at each state identified with h in G, a transition with input label x is pruned when the following condition holds: where h is the backoff sequence associate with h and X x k is the set of output labels of all the outgoing transitions with input label x of the state identified with k. We used the AT&T Natural Voices Product speech synthesis system to synthesize 107,987 AP news articles, generating a large corpus of 8,731,662 unit sequences representing a total of 415,227,388 units.