current_position

element_index_type libsemigroups::FroidurePin::current_position(const_reference x) const

Returns the position of the element x in the semigroup if it is already known to belong to the semigroup.

This member function finds the position of the element x in the semigroup if it is already known to belong to the semigroup, and libsemigroups::UNDEFINED if not. If the semigroup is not fully enumerated, then this member function may return libsemigroups::UNDEFINED when x is in the semigroup, but this is not yet known.

See

FroidurePin::position and FroidurePin::sorted_position.