Various pruning and data organization techniques have been adopted to reduce the effective size of the search space. Hearsay II also used an explicit control strategy to determine what area of the problem to focus on. Then, Harpy used matching templates of phonemes against the input to find the most probable path through the lattice. The harpy speech understanding system . Trends In Speech Recognition, 1980.
Practical decoders make extensive use of pruning.
The art in the design and implementation of decoders is in quickly discarding as much of the search space as possible without losing the correct answer. Beams limit the extent of the search space considered during Viterbi decoding so that the decoder expends search effort in a narrow region where the most probable hypothesis is likely to reside. In W. A. Lea, editor, Trends in Speech Recognition. Prentice Hall, Englewood Cliffs, New Jersey, 1980. No context found.