#include #include #include typedef CGAL::Generalized_map<2> GMap_2; typedef GMap_2::Dart_handle Dart_handle; int main() { GMap_2 gm; Dart_handle dh=gm.make_combinatorial_polygon(4); gm.sew<2>(dh, gm.alpha<1,0,1,0>(dh)); gm.display_characteristics(std::cout); std::cout<<", valid="<