Segment_3 lexicographically_ordered(const Segment_3& s) { if (CGAL::lexicographically_xyz_smaller(s.source(), s.target())) return s; return s.opposite(); }
bool Boundary_slice_chords::retired(const Segment_3& chord) { return (_retired.find(chord) != _retired.end() || _retired.find(chord.opposite()) != _retired.end()); }