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This operation determinizes a weighted transducer. The result will be an equivalent FST that has the property that no state has two transitions with the same input label. For this algorithm, epsilon transitions are treated as regular symbols (cf. RmEpsilon).

The transducer must be functional. The weights must be (weakly) left divisible (valid for TropicalWeight and LogWeight for instance) and zero-sum-free.


template <class Arc>
void Determinize(const Fst<Arc> &ifst, MutableFst<Arc> *ofst);
doc [bad link?]
template <class Arc> DeterminizeFst<Arc>::
DeterminizeFst(const Fst<Arc> &fst);
fstdeterminize a.fst out.fst





Determinize of A:


fstdeterminize a.fst out.fst


  • Determinizable: exponential (polynomial in the size of the output)
  • Non-determinizable: does not terminate
  • Determinizable: exponential (polynomial in the size of the output)
  • Non-determinizable: does not terminate

The determinizable automata include all unweighted and all acyclic input.


Epsilons may be added as input labels at the ends of paths when determinizing transducers. If input transducer also contains epsilons, this may result in a non-deterministic result even when the epsilons are treated as regular symbols. The subsequential label can be chosen as a non-zero value to avoid this issue by passing it as an option (in a variant call to this function/class).

Non-functional transducers can be handled by passing the 'disambiguate_output' option when the semiring has the path property (in a variant call to this function/class). In this case, only the shortest path output for each input is retained.

See Also

Disambiguate, RmEpsilon


-- MichaelRiley - 20 Jun 2007

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Topic revision: r13 - 2014-05-06 - MichaelRiley
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