MinimalRepOrc

Defined in sims.hpp.

This class is a helper for Sims1, calling the word_graph member function attempts to find a right congruence, represented as an WordGraph, with the minimum possible number of nodes such that the action of the semigroup or monoid defined by the presentation consisting of its presentation on the nodes of the WordGraph corresponds to a semigroup of size target_size.

If no such WordGraph can be found, then an empty WordGraph is returned (with 0 nodes and 0 edges).

Inheritance diagram for MinimalRepOrc:

Public Member Functions
	MinimalRepOrc ()
	Default constructor.
MinimalRepOrc &	init ()
	Reinitialize an existing MinimalRepOrc object.
size_t	target_size () const noexcept
	Get the current target size.
MinimalRepOrc &	target_size (size_t val) noexcept
	Set the target size.
Sims1::word_graph_type	word_graph () const
	Get the word graph.
Public Member Functions inherited from SimsSettings< MinimalRepOrc >
	SimsSettings ()
	SimsSettings (SimsSettings &&that)
	SimsSettings (SimsSettings const &that)
	SimsSettings (SimsSettings< OtherSubclass > const &that)
	Construct from SimsSettings with different subclass.
MinimalRepOrc &	add_excluded_pair (Iterator1 first1, Iterator2 last1, Iterator3 first2, Iterator4 last2)
	Add an excluded pair via iterators.
MinimalRepOrc &	add_excluded_pair_no_checks (Iterator1 first1, Iterator2 last1, Iterator3 first2, Iterator4 last2)
	Add an excluded pair via iterators (no checks).
MinimalRepOrc &	add_included_pair (Iterator1 first1, Iterator2 last1, Iterator3 first2, Iterator4 last2)
	Add an included pair via iterators (no checks).
MinimalRepOrc &	add_included_pair_no_checks (Iterator1 first1, Iterator2 last1, Iterator3 first2, Iterator4 last2)
	Add an included pair via iterators.
MinimalRepOrc &	add_pruner (Func &&func)
	Add a pruner to the search tree.
std::vector< word_type >::const_iterator	cbegin_long_rules () const noexcept
	Get the pointer to the first long rule.
MinimalRepOrc &	cbegin_long_rules (size_t pos)
	Set the beginning of the long rules (position).
MinimalRepOrc &	cbegin_long_rules (std::vector< word_type >::const_iterator it)
	Set the beginning of the long rules (iterator).
MinimalRepOrc &	clear_excluded_pairs ()
	Clear the set of excluded words.
MinimalRepOrc &	clear_included_pairs ()
	Clear the set of included pairs.
MinimalRepOrc &	clear_long_rules ()
	Clear the set of long rules.
MinimalRepOrc &	clear_pruners ()
	Clear the set of pruners.
std::vector< word_type > const &	excluded_pairs () const noexcept
	Get the set of pairs that must be excluded from every congruence.
size_t	idle_thread_restarts () const noexcept
	Get the idle thread restart attempt count.
MinimalRepOrc &	idle_thread_restarts (size_t val)
	Set the idle thread restart attempt count.
std::vector< word_type > const &	included_pairs () const noexcept
	Get the set of pairs that must be included in every congruence.
MinimalRepOrc &	init ()
	Reinitialize an existing SimsSettings object.
MinimalRepOrc &	init (SimsSettings< OtherSubclass > const &that)
	Initialize from SimsSettings with different subclass.
MinimalRepOrc &	long_rule_length (size_t val)
	Set the length of a long rule.
size_t	number_of_long_rules () const noexcept
	Returns the number of rules marked as long rules.
size_t	number_of_threads () const noexcept
	Get the number of threads.
MinimalRepOrc &	number_of_threads (size_t val)
	Set the number of threads.
SimsSettings &	operator= (SimsSettings &&that)
SimsSettings &	operator= (SimsSettings const &that)
Presentation< word_type > const &	presentation () const noexcept
	Get the presentation over which the congruences produced by an instance are defined.
MinimalRepOrc &	presentation (Presentation< word_type > const &p)
	Set the presentation over which the congruences produced by an instance are defined.
auto const &	pruners () const noexcept
	Get all active pruners of the search tree.
SimsSettings const &	settings () const noexcept
SimsStats &	stats () const noexcept
	Get the current stats object.
void	throw_if_letter_not_in_alphabet (Iterator1 first, Iterator2 last) const
	Throws if any letter in a range is out of bounds.

Additional Inherited Members
Public Types inherited from SimsSettings< MinimalRepOrc >
using	label_type
	Type for the labels in the associated WordGraph objects.
using	letter_type
	Type for letters in the underlying presentation.
using	node_type
	Type for the nodes in the associated WordGraph objects.
using	size_type
	The size_type of the associated WordGraph objects.
using	word_graph_type
	The type of the associated WordGraph objects.

Member Function Documentation

init()

MinimalRepOrc & init ( )

inline

This function puts a MinimalRepOrc object back into the same state as if it had been newly default constructed.

Returns

A reference to this.

Exceptions

This function guarantees not to throw a LibsemigroupsException.

target_size() [1/2]

size_t target_size ( ) const

inlinenodiscardnoexcept

This function returns the current value for the target size, i.e. the desired size of the transformation semigroup corresponding to the WordGraph returned by the function word_graph.

Returns

A value of type size_t.

Exceptions

This function is noexcept and is guaranteed never to throw.

target_size() [2/2]

MinimalRepOrc & target_size ( size_t val )

inlinenoexcept

This function sets the target size, i.e. the desired size of the transformation semigroup corresponding to the WordGraph returned by the function word_graph.

Parameters

val	the target size.

Returns

A reference to this.

Exceptions

This function is noexcept and is guaranteed never to throw.

word_graph()

Sims1::word_graph_type word_graph ( ) const

nodiscard

This function attempts to find a right congruence, represented as an WordGraph, with the minimum possible number of nodes such that the action of the semigroup or monoid defined by its presentation on the nodes of the WordGraph corresponds to a semigroup of size target_size.

If no such WordGraph can be found, then an empty WordGraph is returned (with 0 nodes and 0 edges).

The algorithm implemented by this function repeatedly runs:

RepOrc(*this)
   .min_nodes(1)
   .max_nodes(best)
   .target_size(target_size())
   .word_graph();

where best is initially target_size, until the returned WordGraph is empty, and then the penultimate WordGraph is returned (if any).

Returns

A value of type WordGraph<uint32_t>.

Exceptions

This function guarantees not to throw a LibsemigroupsException.

Warning

The return value of this function is recomputed every time it is called.

If the return value of number_of_threads is greater than 1, then the value returned by this function is non-deterministic, and may vary even for the same parameters.

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

• /Users/jdm/libsemigroups/include/libsemigroups/sims.hpp