MOTIVATION FOR LATTICE GENERATION
Multiple-pass decoding is time and memory efficient for large
scale speech recognition. Lattice generation generates a word graph
with the N-best hypothesis, thus can efficiently constrain the
search space for the second pass of decoding -- lattice rescoring.
Lattices provide nice framework for multi-pass decoding,
and lattice is a convenient structure to store N-best hypothesis.
ISIP decoder currently operates in the lattice rescoring mode.