METHOD AND APPARATUS FOR GENERATING DETERMINISTIC APPROXIMATE WEIGHTED FINITE-STATE AUTOMATA

An approximate weighted finite-state automaton can be constructed in place of a weighted finite-state automaton so long as the approximate weighted finite-state automaton maintains a sufficient portion of the original best strings in the weighted finite-state automaton and sufficiently few spurious strings are introduced into the approximate weighted finite-state automaton compared to the weighted finite-state automaton. An approximate weighted finite-state automaton can be created from a non-deterministic weighted finite-state automaton during determinization by discarding the requirement that old states be used in place of new states only when an old state is identical to a new state. Instead, in an approximate weighted finite-state automaton, old states will be used in place of new states when each of the remainders of the new state is sufficiently close to the corresponding remainder of the old state. An error tolerance parameter .tau. defines whether the remainders of the new state are sufficiently close to the corresponding remainders of the old state. If the remainders of the new state are sufficiently close to the remainders of the old state, a new transition is created from a current state to the old state rather than the new state. Such approximate weighted finite-state automata allow the size of the resulting deterministic finite-state automata to be reduced and can prevent the expansion that would otherwise occur in some deterministic finite-state automata.