Editing Finite-state transducer (section)

{{Short description|Finite state machine with two tapes (input, output)}}
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A '''finite-state transducer''' ('''FST''') is a [[finite-state machine]] with two memory ''tapes'', following the terminology for [[Turing machine]]s: an input tape and an output tape. This contrasts with an ordinary [[finite-state automaton]], which has a single tape.  An FST is a type of finite-state automaton (FSA) that maps between two sets of symbols.<ref>{{Cite book|title=Speech and Language Processing|last=Jurafsky|first=Daniel|publisher=Pearson|year=2009|isbn=9789332518414}}</ref>  An FST is more general than an FSA.  An FSA defines a [[formal language]] by defining a set of accepted strings, while an FST defines a [[Finitary relation|relation]] between sets of strings.

An FST will read a set of strings on the input tape and generate a set of relations on the output tape.  An FST can be thought of as a translator or relater between strings in a set.

In [[morphological parsing]], an example would be inputting a string of letters into the FST, the FST would then output a string of [[morphemes]].