DifferenceDoc < FST

---+ Difference

---++ Description

This operation computes the difference between two FSAs.   Only strings that are in
the first automaton but not in second are retained in the result.


The first argument must be an [[FstGlossary#AcceptorDef][acceptor]]; the second argument must be an
unweighted, [[FstGlossary#EpsilonDef][epsilon-free]], [[FstGlossary#DeterministicDef][deterministic]] acceptor.  The output labels
of the first acceptor or the input labels of the second acceptor
must be [[ArcSortDoc][sorted]]  (or the FSTs otherwise support appropriate [[FstQuickTour#FstMatcher][matchers]]).
---++ Usage

|<verbatim>
template <class Arc> 
void Difference(const Fst<Arc> &ifsa1, const Fst<Arc> &ifsa2, MutableFst<Arc> *ofsa);
</verbatim>|  |
|<verbatim>
template <class Arc> DifferenceFst<Arc>::
DifferenceFst(const Fst<Arc> &fsa1, const Fst<Arc> &fsa2);
</verbatim>| %DOX{fst::DifferenceFst[%H%]}% |
|<verbatim>
fstdifference [--opts] a.fsa b.fsa out.fsa
  --connect: Trim output (def: true)
</verbatim> | |

---++ Examples

---+++ =A=:

%ATTACHURL%/difference1.jpg

---+++ =B=:


%ATTACHURL%/difference2.jpg

---+++ =A - B=:

%ATTACHURL%/difference3.jpg

<verbatim>
Difference(A, B, &C);
DifferenceFst<Arc>(A, B);
fstdifference a.fsa b.fsa out.fsa
</verbatim>

---++ Complexity

Same as _[[ComposeDoc#ComposeComplexity][Compose]]_.

---++ Caveats

Same as _[[ComposeDoc#ComposeCaveats][Compose]]_.

-- Main.MichaelRiley - 30 Jun 2007

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
jpg	difference1.jpg	r2 r1	manage	9.3 K	2007-06-30 - 16:41	MichaelRiley
jpg	difference2.jpg	r3 r2 r1	manage	7.7 K	2007-06-30 - 16:57	MichaelRiley
jpg	difference3.jpg	r4 r3 r2 r1	manage	11.2 K	2007-06-30 - 16:58	MichaelRiley

This topic: FST > WebHome > FstQuickTour > DifferenceDoc
Topic revision: r5 - 2018-04-27 - MichaelRiley