spot::scc_info Class Reference

Compute an SCC map and gather assorted information. More...

#include <spot/twaalgos/sccinfo.hh>

Collaboration diagram for spot::scc_info:

Public Types
typedef scc_info_node	scc_node
typedef scc_info_node::scc_succs	scc_succs
typedef spot::edge_filter_choice	edge_filter_choice
typedef spot::edge_filter	edge_filter

Public Member Functions
const_twa_graph_ptr	get_aut () const
scc_info_options	get_options () const
edge_filter	get_filter () const
void *	get_filter_data () const
unsigned	scc_count () const
int	one_accepting_scc () const
	Return the number of one accepting SCC if any, -1 otherwise.
bool	reachable_state (unsigned st) const
unsigned	scc_of (unsigned st) const
std::vector< scc_node >::const_iterator	begin () const
std::vector< scc_node >::const_iterator	end () const
std::vector< scc_node >::const_iterator	cbegin () const
std::vector< scc_node >::const_iterator	cend () const
std::vector< scc_node >::const_reverse_iterator	rbegin () const
std::vector< scc_node >::const_reverse_iterator	rend () const
const std::vector< unsigned > &	states_of (unsigned scc) const
internal::scc_edges< const twa_graph::graph_t, internal::keep_all >	edges_of (unsigned scc) const
	A fake container to iterate over all edges leaving any state of an SCC.
internal::scc_edges< const twa_graph::graph_t, internal::keep_inner_scc >	inner_edges_of (unsigned scc) const
	A fake container to iterate over all edges between states of an SCC.
unsigned	one_state_of (unsigned scc) const
unsigned	initial () const
	Get number of the SCC containing the initial state.
const scc_succs &	succ (unsigned scc) const
bool	is_trivial (unsigned scc) const
acc_cond::mark_t	acc (unsigned scc) const
bool	is_accepting_scc (unsigned scc) const
bool	is_rejecting_scc (unsigned scc) const
bool	is_maximally_accepting_scc (unsigned scc) const
	Whether a cycle going through all edges of the SCC is accepting.
void	determine_unknown_acceptance ()
	Study the SCCs that are currently reported neither as accepting nor as rejecting because of the presence of Fin sets.
bool	check_scc_emptiness (unsigned n) const
	Recompute whether an SCC is accepting or not.
void	get_accepting_run (unsigned scc, twa_run_ptr r) const
	Retrieves an accepting run of the automaton whose cycle is in the SCC.
bool	is_useful_scc (unsigned scc) const
bool	is_useful_state (unsigned st) const
std::vector< std::set< acc_cond::mark_t > >	marks () const
	Returns, for each accepting SCC, the set of all marks appearing in it.
std::set< acc_cond::mark_t >	marks_of (unsigned scc) const
std::vector< std::set< acc_cond::mark_t > >	used_acc () const
std::set< acc_cond::mark_t >	used_acc_of (unsigned scc) const
acc_cond::mark_t	acc_sets_of (unsigned scc) const
	Returns, for a given SCC, the set of all colors appearing in it. It is the set of colors that appear in some mark among those returned by marks_of().
acc_cond::mark_t	common_sets_of (unsigned scc) const
std::vector< bool >	weak_sccs () const
bdd	scc_ap_support (unsigned scc) const
std::vector< twa_graph_ptr >	split_on_sets (unsigned scc, acc_cond::mark_t sets, bool preserve_names=false) const
	Split an SCC into multiple automata separated by some acceptance sets.
std::vector< unsigned >	states_on_acc_cycle_of (unsigned scc) const
	: Get all states visited by any accepting cycles of the 'scc'.
	scc_info (const_twa_graph_ptr aut, unsigned initial_state=~0U, edge_filter filter=nullptr, void *filter_data=nullptr, scc_info_options options=scc_info_options::ALL)
	Create the scc_info map for aut.
	scc_info (const_twa_graph_ptr aut, scc_info_options options)
	Create the scc_info map for aut.
	scc_info (const scc_and_mark_filter &filt, scc_info_options options)
	Create an scc_info map from some filter.
	scc_info (const scc_and_mark_filter &filt)
	Create an scc_info map from some filter.

Protected Member Functions
void	determine_usefulness ()
const scc_node &	node (unsigned scc) const
void	states_on_acc_cycle_of_rec (unsigned scc, acc_cond::mark_t all_fin, acc_cond::mark_t all_inf, unsigned nb_pairs, std::vector< acc_cond::rs_pair > &pairs, std::vector< unsigned > &res, std::vector< unsigned > &old) const
	: Recursive function used by states_on_acc_cycle_of().

Protected Attributes
std::vector< unsigned >	sccof_
std::vector< scc_node >	node_
const_twa_graph_ptr	aut_
unsigned	initial_state_
edge_filter	filter_
void *	filter_data_
int	one_acc_scc_ = -1
scc_info_options	options_

Detailed Description

Compute an SCC map and gather assorted information.

This takes twa_graph as input and compute its SCCs. This class maps all input states to their SCCs, and vice versa. It allows iterating over all SCCs of the automaton, and checks their acceptance or non-acceptance.

SCC are numbered in reverse topological order, i.e. the SCC of the initial state has the highest number, and if s1 is reachable from s2, then s1 < s2. Many algorithms depend on this property to determine in what order to iterate the SCCs.

Additionally this class can be used on alternating automata, but in this case, universal transitions are handled like existential transitions. It still makes sense to check which states belong to the same SCC, but the acceptance information computed by this class is meaningless.

Constructor & Destructor Documentation

scc_info() [1/4]

spot::scc_info::scc_info	(	const_twa_graph_ptr	aut,
		unsigned	initial_state = ~0U,
		edge_filter	filter = nullptr,
		void *	filter_data = nullptr,
		scc_info_options	options = scc_info_options::ALL )

Create the scc_info map for aut.

References spot::ALL.

Referenced by scc_info(), and scc_info().

scc_info() [2/4]

spot::scc_info::scc_info ( const_twa_graph_ptr aut, scc_info_options options )

inline

Create the scc_info map for aut.

References scc_info(), and spot::U.

scc_info() [3/4]

spot::scc_info::scc_info	(	const scc_and_mark_filter &	filt,
		scc_info_options	options )

Create an scc_info map from some filter.

This is usually used to prevent some edges from being considered as part of cycles, and can additionally restrict to exploration to some SCC discovered by another SCC.

scc_info() [4/4]

spot::scc_info::scc_info ( const scc_and_mark_filter & filt )

inline

Create an scc_info map from some filter.

This is usually used to prevent some edges from being considered as part of cycles, and can additionally restrict to exploration to some SCC discovered by another SCC.

References scc_info(), and spot::ALL.

Member Function Documentation

acc_sets_of()

acc_cond::mark_t spot::scc_info::acc_sets_of ( unsigned scc ) const

inline

Returns, for a given SCC, the set of all colors appearing in it. It is the set of colors that appear in some mark among those returned by marks_of().

Referenced by is_maximally_accepting_scc().

check_scc_emptiness()

bool spot::scc_info::check_scc_emptiness

(

unsigned

n

)

const

Recompute whether an SCC is accepting or not.

This is an internal function of determine_unknown_acceptance().

common_sets_of()

acc_cond::mark_t spot::scc_info::common_sets_of ( unsigned scc ) const

inline

Returns, for a given SCC, the set of colors that appear on all of its transitions.

determine_unknown_acceptance()

void spot::scc_info::determine_unknown_acceptance

(

)

Study the SCCs that are currently reported neither as accepting nor as rejecting because of the presence of Fin sets.

This simply calls check_scc_emptiness() on undeterminate SCCs.

edges_of()

internal::scc_edges< const twa_graph::graph_t, internal::keep_all > spot::scc_info::edges_of ( unsigned scc ) const

inline

A fake container to iterate over all edges leaving any state of an SCC.

The difference with inner_edges_of() is that edges_of() include outgoing edges from all the states, even if they leave the SCC.

get_accepting_run()

void spot::scc_info::get_accepting_run	(	unsigned	scc,
		twa_run_ptr	r ) const

Retrieves an accepting run of the automaton whose cycle is in the SCC.

Parameters

scc	an accepting scc
r	a run to fill

This method needs the STOP_ON_ACC option.

References spot::STOP_ON_ACC, and spot::TRACK_SUCCS.

initial()

unsigned spot::scc_info::initial ( ) const

inline

Get number of the SCC containing the initial state.

inner_edges_of()

internal::scc_edges< const twa_graph::graph_t, internal::keep_inner_scc > spot::scc_info::inner_edges_of ( unsigned scc ) const

inline

A fake container to iterate over all edges between states of an SCC.

The difference with edges_of() is that inner_edges_of() ignores edges leaving the SCC. In the case of an alternating automaton, an edge is considered to be part of the SCC of one of its destination is in the SCC.

is_maximally_accepting_scc()

bool spot::scc_info::is_maximally_accepting_scc ( unsigned scc ) const

inline

Whether a cycle going through all edges of the SCC is accepting.

References acc_sets_of().

marks()

std::vector< std::set< acc_cond::mark_t > > spot::scc_info::marks

(

)

const

Returns, for each accepting SCC, the set of all marks appearing in it.

References marks().

Referenced by marks().

one_accepting_scc()

int spot::scc_info::one_accepting_scc ( ) const

inline

Return the number of one accepting SCC if any, -1 otherwise.

If an accepting SCC has been found, return its number. Otherwise return -1. Note that when the acceptance condition contains Fin, -1 does not imply that all SCCs are rejecting: it just means that no accepting SCC is known currently. In that case, you might want to call determine_unknown_acceptance() first.

split_on_sets()

std::vector< twa_graph_ptr > spot::scc_info::split_on_sets	(	unsigned	scc,
		acc_cond::mark_t	sets,
		bool	preserve_names = false ) const

Split an SCC into multiple automata separated by some acceptance sets.

Pretend that the transitions of SCC scc that belong to any of the sets given in sets have been removed, and return a set of automata with disjoint sets of transitions that cover all cycles that remain after the removal. Two cycles that share a state are guaranteed to be in the same automaton. State and transitions that do not belong to any cycle after removal may or may not be covered by the returned automata. All returned automata have at least one edge, but it is also possible that they may not contain any cycle.

Set preserve_names to True if you want to keep the original name of each states for display. (This is a bit slower.)

This method was originally used as a part of our generic emptiness check [baier.19.atva] . However, creating new automata made it quite slow, so today our generic emptiness check does not use split_on_sets(). Instead, it passes an scc_and_mark_filter to scc_info in order to explore SCCs while ignoring edges with some given colors and without any copy.

See also

scc_and_mark_filter

generic_emptiness_check_for_scc

states_on_acc_cycle_of()

std::vector< unsigned > spot::scc_info::states_on_acc_cycle_of

(

unsigned

scc

)

const

: Get all states visited by any accepting cycles of the 'scc'.

Throws an exception if the automaton does not have a 'Streett-like' acceptance condition.

states_on_acc_cycle_of_rec()

void spot::scc_info::states_on_acc_cycle_of_rec ( unsigned scc, acc_cond::mark_t all_fin, acc_cond::mark_t all_inf, unsigned nb_pairs, std::vector< acc_cond::rs_pair > & pairs, std::vector< unsigned > & res, std::vector< unsigned > & old ) const

protected

: Recursive function used by states_on_acc_cycle_of().

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The documentation for this class was generated from the following file:

• spot/twaalgos/sccinfo.hh