14. The apparatus of claim 10 , wherein the WFST is dynamically composed to a second WFST using a single lookup arc cache for the second WFST, wherein the single lookup arc cache includes cache entries for input labels that are recursively reachable by epsilon arcs in the second WFST.
14. The apparatus of claim 10 , wherein the WFST is dynamically composed to a second WFST using a single lookup arc cache for the second WFST, wherein the single lookup arc cache includes cache entries for input labels that are recursively reachable by epsilon arcs in the second WFST. 15. The apparatus of claim 14 , wherein each entry in the single lookup arc cache includes a source state identifier, an input label identifier, an arc identifier, and an accumulated weight value, wherein the accumulated weight value corresponds to the weight of the arcs along the path from the state identified by the source state identifier to the arc identified by the arc identifier.