7. The apparatus of claim 6 , wherein the WFST decoder further executes instructions to: look up in the single lookup arc cache the arc identifier and accumulated weight for an input label and a source state; and receive from the single lookup arc cache the arc identifier and accumulated weight for the input label and the source state.
6. The apparatus of claim 5 , 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.