edu.cmu.sphinx.fst.operations

Class Compose

java.lang.Object

edu.cmu.sphinx.fst.operations.Compose

public class Compose
extends java.lang.Object

Compose operation. See: M. Mohri, "Weighted automata algorithms", Handbook of Weighted Automata. Springer, pp. 213-250, 2009.

Method Summary

Modifier and Type	Method and Description
static void	augment(int label, Fst fst, Semiring semiring) Augments the labels of an Fst in order to use it for composition avoiding multiple epsilon paths in the resulting Fst Augment can be applied to both Fst and ImmutableFst, as immutable fsts hold an additional null arc for that operation
static Fst	compose(Fst fst1, Fst fst2, Semiring semiring, boolean sorted) Computes the composition of two Fsts.
static Fst	get(Fst fst1, Fst fst2, Semiring semiring) Computes the composition of two Fsts.
static Fst	getFilter(java.lang.String[] syms, Semiring semiring) Get a filter to use for avoiding multiple epsilon paths in the resulting Fst See: M.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

compose

public static Fst compose(Fst fst1,
                          Fst fst2,
                          Semiring semiring,
                          boolean sorted)

Computes the composition of two Fsts. Assuming no epsilon transitions. Input Fsts are not modified.

Parameters:

fst1 - the first Fst

fst2 - the second Fst

semiring - the semiring to use in the operation

sorted - sort result

Returns:

the composed Fst

get

public static Fst get(Fst fst1,
                      Fst fst2,
                      Semiring semiring)

Computes the composition of two Fsts. The two Fsts are augmented in order to avoid multiple epsilon paths in the resulting Fst

Parameters:

fst1 - the first Fst

fst2 - the second Fst

semiring - the semiring to use in the operation

Returns:

the composed Fst

getFilter

public static Fst getFilter(java.lang.String[] syms,
                            Semiring semiring)

Get a filter to use for avoiding multiple epsilon paths in the resulting Fst See: M. Mohri, "Weighted automata algorithms", Handbook of Weighted Automata. Springer, pp. 213-250, 2009.

Parameters:

syms - the gilter's input/output symbols

semiring - the semiring to use in the operation

Returns:

the filter

augment

public static void augment(int label,
                           Fst fst,
                           Semiring semiring)

Augments the labels of an Fst in order to use it for composition avoiding multiple epsilon paths in the resulting Fst Augment can be applied to both Fst and ImmutableFst, as immutable fsts hold an additional null arc for that operation

Parameters:

label - constant denoting if the augment should take place on input or output labels For value equal to 0 augment will take place for input labels For value equal to 1 augment will take place for output labels

fst - the fst to augment

semiring - the semiring to use in the operation