Transducer Layer

Datatypes
typedef TransducerHandle	TransducerHandle
	A finite state transducer (FST).
Constructive and Destructive Functions for Elementary Transducers
TransducerHandle	create_empty_transducer ()
	Create an empty transducer.
TransducerHandle	create_epsilon_transducer ()
	Create an epsilon transducer.
TransducerHandle	define_transducer (Key k)
	Create a transducer that accepts one occurrence of key identity pair k:k.
TransducerHandle	define_transducer (KeyPair *p)
	Create a transducer that accepts one occurrence of key pair p.
TransducerHandle	define_transducer (KeySet *ks)
	Create a transducer that accepts the union of the key identity pairs in a set ks.
TransducerHandle	define_transducer (KeyPairSet *Pi)
	Create a transducer that accepts the union of the key pairs in a set Pi.
KeyPairSet *	define_keypair_set (TransducerHandle t)
	Define a set of pairs by collecting all key pairs in transducer t.
KeySet *	define_key_set (TransducerHandle t)
	Define a set of keys by collecting all keys in transducer t.
TransducerHandle	add_weight (TransducerHandle t, float w)
	Add weight w to transducer t.
void	delete_transducer (TransducerHandle t)
	Delete transducer t.
Basic Algebraic Functions
TransducerHandle	compose (TransducerHandle t1, TransducerHandle t2, bool destructive=true)
	Composition of t1 and t2.
TransducerHandle	concatenate (TransducerHandle t1, TransducerHandle t2)
	Concatenation of t1 and t2.
TransducerHandle	copy (TransducerHandle t)
	A deep copy of t.
TransducerHandle	disjunct (TransducerHandle t1, TransducerHandle t2)
	Disjunction of t1 and t2.
TransducerHandle	disjunct_transducers_as_tries (TransducerHandle t1, TransducerHandle t2)
	Disjunction of t1 and t2 that are both tries. The resulting transducer is also a trie.
TransducerHandle	disjunct_as_trie (TransducerHandle t, KeyVector *key_string, float weight=0, bool sum_weights=false)
	Add the KeyVector * key_string as a path to the trie t.
TransducerHandle	disjunct_as_trie (TransducerHandle t, KeyPairVector *key_pair_string, float weight=0, bool sum_weights=false)
	Add the KeyPairVector * key_pair_string as a path to the trie t.
TransducerHandle	extract_input_language (TransducerHandle t)
	Extract the input language of t.
TransducerHandle	extract_output_language (TransducerHandle t)
	Extract the output language of t.
TransducerHandle	intersect (TransducerHandle t1, TransducerHandle t2)
	Intersection of t1 and t2.
TransducerHandle	intersecting_composition (TransducerHandle t, vector< TransducerHandle > *v, KeyTable *kt=NULL)
	The intersecting composition of t with the transducers in v.
TransducerHandle	invert (TransducerHandle t)
	Switch input and output in the transition pairs of transducer t.
TransducerHandle	negate (TransducerHandle t, KeyPairSet *Pi)
	Complement of t with regard to a set of key pairs Pi.
TransducerHandle	optionalize (TransducerHandle t)
	Disjunction of t and epsilon.
TransducerHandle	repeat_le_n (TransducerHandle t, int n)
	Transducer t repeated at most n times.
TransducerHandle	repeat_n (TransducerHandle t, int n)
	t catenated n times.
TransducerHandle	repeat_plus (TransducerHandle t)
	Transducer t +.
TransducerHandle	repeat_star (TransducerHandle t)
	Transducer t *.
TransducerHandle	reverse (TransducerHandle t)
	Reverse transducer t.
TransducerHandle	subtract (TransducerHandle t1, TransducerHandle t2)
	t1 minus t2.
Substitution, Insertion and Removal functions
TransducerHandle	add_input_language (TransducerHandle t, KeyPairSet *Pi)
	Add input language to t using a set of feasible pairs in Pi.
TransducerHandle	add_output_language (TransducerHandle t, KeyPairSet *Pi)
	Add output language to t using a set of feasible pairs in Pi.
TransducerHandle	insert_freely (TransducerHandle t, KeyPair *p)
	Freely insert key pair p into t.
TransducerHandle	remove_pair (TransducerHandle t, KeyPair *p)
	Remove transitions that are equal to key pair p.
TransducerHandle	remove_pairs (TransducerHandle t, KeySet *ks)
	Remove transitions where a key from ks is used on both the input and output sides.
TransducerHandle	shuffle (TransducerHandle t1, TransducerHandle t2)
	Shuffle t1 and t2.
TransducerHandle	substitute_key (TransducerHandle t, Key k1, Key k2, bool ignore_epsilon_pairs=false)
	In all transitions, substitute key k1 with key k2.
TransducerHandle	substitute_key (TransducerHandle t, KeySet *ks, Key k2)
	In all transitions, if a key is equal to some key in key set ks, substitute it with key k2.
TransducerHandle	substitute_with_pair (TransducerHandle t, KeyPair *p1, KeyPair *p2)
	Substitute all transitions equal to p1 with a copy of p2.
TransducerHandle	substitute_with_transducer (TransducerHandle t, KeyPair *p, TransducerHandle tr)
	Substitute all transitions in transducer t equal to p with a copy of transducer tr.
Optimizing and Converting Functions
TransducerHandle	determinize (TransducerHandle t)
	Determinize t.
vector< TransducerHandle >	find_all_paths (TransducerHandle t, bool unique=false)
	Find all paths from initial to final state in transducer t. unique defines whether t is determinized before finding paths.
TransducerHandle	find_best_paths (TransducerHandle t, int n, bool unique=false)
	n best paths from initial to final state in transducer t. unique defines whether equal paths are included only once.
TransducerHandle	find_random_paths (TransducerHandle t, int max_number, bool unique=false)
	For unweighted transducers: find a maximum of max_number random paths in transducer t. unique defines whether equal paths are included only once.
TransducerHandle	minimize (TransducerHandle t)
	Minimize t.
TransducerHandle	push_weights (TransducerHandle t, bool initial)
	Push weights in transducer t towards the initial state, if initial is true, otherwise towards the final state.
TransducerHandle	modify_weights (TransducerHandle t, float(*modify)(float), bool modify_transition_weights=false)
	Modify final weights of transducer t according to function modify. modify_transition_weights defines whether transition weights are modified as well.
TransducerHandle	remove_epsilons (TransducerHandle t)
	Remove from t transitions whose input and output labels are epsilons.
Testing Functions
These functions do not delete their arguments.
bool	are_equivalent (TransducerHandle t1, TransducerHandle t2)
	Whether t1 and t2 are equivalent.
bool	are_disjoint (TransducerHandle t1, TransducerHandle t2)
	Whether t1 and t2 have an empty intersection.
float	get_weight (TransducerHandle t)
	The total weight of one-path transducer t.
bool	is_automaton (TransducerHandle t)
	Whether for every transition in t the input symbol is the same as the output symbol.
bool	is_cyclic (TransducerHandle t)
	Whether t is cyclic.
bool	is_infinitely_ambiguous (TransducerHandle t, bool output=true, KeyVector *kv=NULL)
	Whether t has infinitely many output strings for some input string (or for a certain input string kv), if output is true and whether it has infinitely many input strings for some output string (or for a certain output string kv), if output is false.
bool	is_deterministic (TransducerHandle t)
	Whether t is deterministic.
bool	is_empty (TransducerHandle t)
	Whether t is the empty transducer.
bool	is_epsilon (TransducerHandle t)
	Whether t is the epsilon transducer.
bool	is_minimal (TransducerHandle t)
	Whether t is a minimal transducer.
bool	is_subset (TransducerHandle t1, TransducerHandle t2)
	Whether t1 is a subset of t2.
KeyVectorVector *	lookup_all (TransducerHandle t, vector< Key > *input_string)
	Look up the output-strings corresponding to string input_string. Return NULL, if there are no output-strings for input-string.
KeyVector *	lookup_first (TransducerHandle t, vector< Key > *input_string)
	Look up the first found output-string corresponding to string input_string. Return NULL, if there are no output-strings for input-string.
Input/Output Functions
Transducers in this layer are not aware of any restrictions to their alphabet or any attributes. Thus the file format for these transducers neither lists the known keys nor the properties of the transducer.
int	read_format (istream &is=cin)
	Read the format of the next transducer in the input stream is.
TransducerHandle	read_transducer (istream &is=cin)
	Read transducer in binary form from input stream is.
TransducerHandle	read_transducer (const char *filename)
	Read a binary transducer from file filename.
TransducerHandle	read_transducer_number (istream &is)
	Read a transducer in AT&T number format from istream is.
void	write_transducer (TransducerHandle t, ostream &os=cout, bool backwards_compatibility=false)
	Write Transducer t in binary form to ostream os.
void	write_transducer (TransducerHandle t, const char *filename, bool backwards_compatibility=false)
	Write transducer t to file filename.
void	print_transducer_number (TransducerHandle t, bool print_weights=true, ostream &os=cout)
	Print transducer t in number format to ostream os. print_weights defines whether weights are printed.

---

Detailed Description

Datatypes and functions related to transducer calculus and support. This layer depends on the Key Layer .

---

Typedef Documentation

typedef TransducerHandle TransducerHandle

A finite state transducer (FST).

A FST is a weighted or an unweighted synchronous finite-state transducer i.e. an automaton representing a set of strings of symbol pairs.

Definition at line 21 of file transducer-layer.h.

---

Function Documentation

TransducerHandle add_input_language	(	TransducerHandle	t,
		KeyPairSet *	Pi
	)

Add input language to t using a set of feasible pairs in Pi.

Equivalent to a composition of transducer t and a transducer accepting any number of pairs in Pi.

TransducerHandle add_output_language	(	TransducerHandle	t,
		KeyPairSet *	Pi
	)

Add output language to t using a set of feasible pairs in Pi.

Equivalent to a composition of a transducer accepting any number of pairs in Pi and transducer t.

TransducerHandle add_weight	(	TransducerHandle	t,
		float	w
	)

Add weight w to transducer t.

Set the weights of all final states in transducer t to w.

Note:

Does nothing if the underlying library does not support weights.

bool are_disjoint	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Whether t1 and t2 have an empty intersection.

Precondition:

t1 and t2 are deterministic

Postcondition:

t1 and t2 are not deleted.

bool are_equivalent	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Whether t1 and t2 are equivalent.

The same that has been said of alignment in function intersect goes for are_equivalent. For example, both [a:b] and [a:0 0:b] map the string "a" to "b", but they are not equivalent because the alignment is different.

Postcondition:

t1 and t2 are not deleted.

TransducerHandle compose	(	TransducerHandle	t1,
		TransducerHandle	t2,
		bool	destructive = true
	)

Composition of t1 and t2.

Parameters:

	t1	first transducer in composition operation
	t2	second transducer in composition operation
	destructive	Whether the argument transducers are deleted.

Composition of t1 and t2 maps "a" to "c" iff t1 maps "a" to some "b" and t2 maps "b" to "c".

Postcondition:

The resulting transducer may be nondeterministic and not minimal. t1 and t2 are deleted.

TransducerHandle concatenate	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Concatenation of t1 and t2.

If t1 maps the string "a" to "b" and t2 maps "c" to "d", then concatenation of t1 and t2 maps the string "ac" to "bd".

Postcondition:

The resulting transducer may contain epsilons and be nondeterministic and not minimal. t1 and t2 are deleted.

TransducerHandle copy

(

TransducerHandle

t

)

A deep copy of t.

Postcondition:

t is not deleted.

TransducerHandle create_empty_transducer

(

)

Create an empty transducer.

Returns:

A transducer that has one state that is not final and has no transitions, i.e. does not accept any string.

TransducerHandle create_epsilon_transducer

(

)

Create an epsilon transducer.

Returns:

A transducer that has one state that is final and has no transitions, i.e. accepts the epsilon string.

KeySet* define_key_set

(

TransducerHandle

t

)

Define a set of keys by collecting all keys in transducer t.

Returns:

A set of keys that contains all keys that occur in transitions of transducer t.

KeyPairSet* define_keypair_set

(

TransducerHandle

t

)

Define a set of pairs by collecting all key pairs in transducer t.

Returns:

A set of pairs that contains all key pairs that occur in transitions of transducer t.

TransducerHandle define_transducer

(

KeyPairSet *

Pi

)

Create a transducer that accepts the union of the key pairs in a set Pi.

Returns:

A disjunction of all key pairs in Pi.

TransducerHandle define_transducer

(

KeySet *

ks

)

Create a transducer that accepts the union of the key identity pairs in a set ks.

Returns:

A disjunction of all key identity pairs in ks.

TransducerHandle define_transducer

(

KeyPair *

p

)

Create a transducer that accepts one occurrence of key pair p.

Returns:

A transducer that has one transition of key pair p.

TransducerHandle define_transducer

(

Key

k

)

Create a transducer that accepts one occurrence of key identity pair k:k.

Returns:

A transducer that has one transition of key identity pair k:k.

void delete_transducer

(

TransducerHandle

t

)

Delete transducer t.

TransducerHandle determinize

(

TransducerHandle

t

)

Determinize t.

Remove transitions whose input and output symbols are epsilons from t and determinize it. After determinization no state in t has two transitions with equal input and output labels.

Postcondition:

t is deleted.

TransducerHandle disjunct	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Disjunction of t1 and t2.

Disjunction of t1 and t2 maps "a" to "b" iff t1 and/or t2 maps "a" to "b".

Postcondition:

t1 and t2 are deleted. The resulting transducer may have epsilons.

TransducerHandle disjunct_as_trie	(	TransducerHandle	t,
		KeyPairVector *	key_pair_string,
		float	weight = 0,
		bool	sum_weights = false
	)

Add the KeyPairVector * key_pair_string as a path to the trie t.

See also:

disjunct_as_trie

TransducerHandle disjunct_as_trie	(	TransducerHandle	t,
		KeyVector *	key_string,
		float	weight = 0,
		bool	sum_weights = false
	)

Add the KeyVector * key_string as a path to the trie t.

Parameters:

	t	The trie where the path is added.
	key_string	A KeyVector representing the path.
	weight	The weight of the path.
	sum_weights	If the path already exists with a different weight: whether (1) a new path is added or (2) the weight of the old path is modified by summing the weights.

TransducerHandle disjunct_transducers_as_tries	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Disjunction of t1 and t2 that are both tries. The resulting transducer is also a trie.

TransducerHandle extract_input_language

(

TransducerHandle

t

)

Extract the input language of t.

Maps "A" to "A" iff t maps "A" to some string "B". For example the argument transducer [ a:b [c:d | e:f] ] gives the result [ a:a [c:c | e:e] ].

Postcondition:

t is deleted.

TransducerHandle extract_output_language

(

TransducerHandle

t

)

Extract the output language of t.

Maps "B" to "B" iff t maps some string "A" to "B". For example the argument transducer [ a:b [c:d | e:f] ] gives the result [ b:b [d:d | f:f] ].

Postcondition:

t is deleted.

vector<TransducerHandle> find_all_paths	(	TransducerHandle	t,
		bool	unique = false
	)

Find all paths from initial to final state in transducer t. unique defines whether t is determinized before finding paths.

Parameters:

	t	The transducer where best paths are searched. Cannot be cyclic.
	unique	Whether equal paths are included only once (i.e whether t is determinized before finding paths).

TransducerHandle find_best_paths	(	TransducerHandle	t,
		int	n,
		bool	unique = false
	)

n best paths from initial to final state in transducer t. unique defines whether equal paths are included only once.

Returns n paths with smallest weight. If t is unweighted, returns n paths that are found first (not necessarily the shortest ones).

Parameters:

	t	The transducer where best paths are searched. Can be cyclic.
	n	Number of paths that are returned.
	unique	Whether equal paths are included only once (i.e whether t is determinized before finding paths).

Returns:

A disjunction of n best paths.

TransducerHandle find_random_paths	(	TransducerHandle	t,
		int	max_number,
		bool	unique = false
	)

For unweighted transducers: find a maximum of max_number random paths in transducer t. unique defines whether equal paths are included only once.

For weighted transducer: the same as find_best_paths. For unweighted transducers, the paths returned and their number may vary randomly.

Parameters:

	t	The transducer where best paths are searched. Can be cyclic.
	max_number	A maximum number of paths that are returned.
	unique	Whether t is determinized before finding paths.

float get_weight

(

TransducerHandle

t

)

The total weight of one-path transducer t.

In HWFST: The sum of all transition weights and the final weight in transducer t. In HFST: Returns always zero.

Precondition:

t is a one-path transducer.

TransducerHandle insert_freely	(	TransducerHandle	t,
		KeyPair *	p
	)

Freely insert key pair p into t.

For example, freely inserting the key pair x:y into the transducer [a b] is equivalent to [x:y]* a [x:y]* b [x:y]*.

Postcondition:

t is deleted.

TransducerHandle intersect	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Intersection of t1 and t2.

Maps string S_1 to string S_2 (length of both strings is n) iff both t1 and t2 map S_1 to S_2 by aligning the i:th symbol in S_1 with the i:th symbol in S_2 for all i in n.

For example, [a:b] and [a:0 0:b] both map a to b, but their intersection is empty because the alignment is different.

Postcondition:

t1 and t2 are deleted.

TransducerHandle intersecting_composition	(	TransducerHandle	t,
		vector< TransducerHandle > *	v,
		KeyTable *	kt = NULL
	)

The intersecting composition of t with the transducers in v.

Intersecting composition of the transducer t and the transducers in the vector v is equivalent to the composition of t with the intersection of the transducers in v. If kt is not NULL, then the keys in kt, which correspond to Xerox-style flag-diacritics will be treated as epsilons, i.e. the will be in the result-transducer, but will not affect the rules in any way.

Postcondition:

The transducer t is deleted.

The transducers in the vector v are deleted.

The vector v is deleted.

The result is not minimized.

TransducerHandle invert

(

TransducerHandle

t

)

Switch input and output in the transition pairs of transducer t.

Inversion of t maps "A" to "B" iff t maps "B" to "A". For example inversion of [a:b c:d e:f] is [b:a d:c f:e].

Postcondition:

t is deleted.

bool is_automaton

(

TransducerHandle

t

)

Whether for every transition in t the input symbol is the same as the output symbol.

Postcondition:

t is not deleted.

bool is_cyclic

(

TransducerHandle

t

)

Whether t is cyclic.

Postcondition:

t is not deleted.

bool is_deterministic

(

TransducerHandle

t

)

Whether t is deterministic.

bool is_empty

(

TransducerHandle

t

)

Whether t is the empty transducer.

t is the empty transducer if it is equivalent to a transducer that has one state that is not final and has no transitions.

Postcondition:

t is not deleted.

bool is_epsilon

(

TransducerHandle

t

)

Whether t is the epsilon transducer.

t is the epsilon transducer if it equivalent to a transducer that has one state that is final and has no transitions.

Postcondition:

t is not deleted.

bool is_infinitely_ambiguous	(	TransducerHandle	t,
		bool	output = true,
		KeyVector *	kv = NULL
	)

Whether t has infinitely many output strings for some input string (or for a certain input string kv), if output is true and whether it has infinitely many input strings for some output string (or for a certain output string kv), if output is false.

Postcondition:

t is not deleted.

bool is_minimal

(

TransducerHandle

t

)

Whether t is a minimal transducer.

bool is_subset	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Whether t1 is a subset of t2.

KeyVectorVector* lookup_all	(	TransducerHandle	t,
		vector< Key > *	input_string
	)

Look up the output-strings corresponding to string input_string. Return NULL, if there are no output-strings for input-string.

KeyVector* lookup_first	(	TransducerHandle	t,
		vector< Key > *	input_string
	)

Look up the first found output-string corresponding to string input_string. Return NULL, if there are no output-strings for input-string.

TransducerHandle minimize

(

TransducerHandle

t

)

Minimize t.

Remove epsilons from t and determinize and minimize it.

Postcondition:

t is deleted.

See also:

remove_epsilons determinize

TransducerHandle modify_weights	(	TransducerHandle	t,
		float(*)(float)	modify,
		bool	modify_transition_weights = false
	)

Modify final weights of transducer t according to function modify. modify_transition_weights defines whether transition weights are modified as well.

TransducerHandle negate	(	TransducerHandle	t,
		KeyPairSet *	Pi
	)

Complement of t with regard to a set of key pairs Pi.

Complement is computed by subtraction: ~t = [.*] - t

Complement of transducer [t] maps the string 'a_1a_2 ... a_n' to 'b_1b_2 ... b_n' iff Pi contains 'a_i:b_i' for all 1 <= i <= n, and t & [a_1:b_1 a_2:b_2 ... a_n:b_n] is the empty transducer. Either a_i or b_i is allowed to be the empty symbol.

The same that has been said of alignment in function intersect goes for negation. For example, both [a:b] and [a:0 0:b] map the string "a" to "b", but the complement of [a:b] nevertheless includes 'a:0 0:b' because the alignment is different.

Postcondition:

t is deleted.

TransducerHandle optionalize

(

TransducerHandle

t

)

Disjunction of t and epsilon.

Postcondition:

t is deleted.

void print_transducer_number	(	TransducerHandle	t,
		bool	print_weights = true,
		ostream &	os = cout
	)

Print transducer t in number format to ostream os. print_weights defines whether weights are printed.

See also:

print_transducer

TransducerHandle push_weights	(	TransducerHandle	t,
		bool	initial
	)

Push weights in transducer t towards the initial state, if initial is true, otherwise towards the final state.

Note:

Does nothing if the underlying implementation does not support weights.

int read_format

(

istream &

is = cin

)

Read the format of the next transducer in the input stream is.

Returns:

• 0 == ordinary unweighted transducer (HFST)
• 1 == weighted transducer (HWFST)
• 2 == compact unweighted transducer (HFST)
• -1 == the end of file has been reached
• -2 == transducer format is unknown or an error has occurred

Postcondition:

is is not changed.

TransducerHandle read_transducer

(

const char *

filename

)

Read a binary transducer from file filename.

TransducerHandle read_transducer

(

istream &

is = cin

)

Read transducer in binary form from input stream is.

TransducerHandle read_transducer_number

(

istream &

is

)

Read a transducer in AT&T number format from istream is.

See also:

read_transducer_text

TransducerHandle remove_epsilons

(

TransducerHandle

t

)

Remove from t transitions whose input and output labels are epsilons.

Create an equivalent transducer that has no transitions whose input and output labels are epsilons.

TransducerHandle remove_pair	(	TransducerHandle	t,
		KeyPair *	p
	)

Remove transitions that are equal to key pair p.

TransducerHandle remove_pairs	(	TransducerHandle	t,
		KeySet *	ks
	)

Remove transitions where a key from ks is used on both the input and output sides.

TransducerHandle repeat_le_n	(	TransducerHandle	t,
		int	n
	)

Transducer t repeated at most n times.

TransducerHandle repeat_n	(	TransducerHandle	t,
		int	n
	)

t catenated n times.

Parameters:

	t	Transducer to be catenated.
	n	How many times t is catenated. If n == 0, an epsilon transducer is returned.

Postcondition:

t is not deleted. [actually it cannot be used]

TransducerHandle repeat_plus

(

TransducerHandle

t

)

Transducer t +.

Transducer that accepts one or more t.

Postcondition:

t is deleted.

TransducerHandle repeat_star

(

TransducerHandle

t

)

Transducer t *.

Transducer that accepts any number of t.

Postcondition:

t is deleted.

TransducerHandle reverse

(

TransducerHandle

t

)

Reverse transducer t.

TransducerHandle shuffle	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

Shuffle t1 and t2.

...

TransducerHandle substitute_key	(	TransducerHandle	t,
		KeySet *	ks,
		Key	k2
	)

In all transitions, if a key is equal to some key in key set ks, substitute it with key k2.

TransducerHandle substitute_key	(	TransducerHandle	t,
		Key	k1,
		Key	k2,
		bool	ignore_epsilon_pairs = false
	)

In all transitions, substitute key k1 with key k2.

Parameters:

	t	Transducer where substitution is made.
	k1	The key that is substituted.
	k2	The substituting key.
	ignore_epsilon_pairs	Whether keys in epsilon:epsilon transitions are not substituted.

TransducerHandle substitute_with_pair	(	TransducerHandle	t,
		KeyPair *	p1,
		KeyPair *	p2
	)

Substitute all transitions equal to p1 with a copy of p2.

TransducerHandle substitute_with_transducer	(	TransducerHandle	t,
		KeyPair *	p,
		TransducerHandle	tr
	)

Substitute all transitions in transducer t equal to p with a copy of transducer tr.

TransducerHandle subtract	(	TransducerHandle	t1,
		TransducerHandle	t2
	)

t1 minus t2.

t1 minus t2 is the transducer which accepts the strings accepted by t1 that are not accepted by t2. The same that has been said of alignment in function intersect goes for subtraction.

For example, both [a:b] and [a:0 0:b] map the string a to b, but the result of a:b - [a:0 0:b] is nevertheless [a:b] because the alignment is different.

Postcondition:

t1 and t2 are deleted.

void write_transducer	(	TransducerHandle	t,
		const char *	filename,
		bool	backwards_compatibility = false
	)

Write transducer t to file filename.

See also:

write_transducer

void write_transducer	(	TransducerHandle	t,
		ostream &	os = cout,
		bool	backwards_compatibility = false
	)

Write Transducer t in binary form to ostream os.

Parameters:

	t	The transducer that is written.
	os	The output stream where the transducer is written.
	backwards_compatibility	Whether the transducer is stored in SFST/OpenFst compatible format.