code: private void interiorAreaInteriorArea_(int half_edge, int id_a, int id_b) {
  		if (m_matrix[MatrixPredicate.InteriorInterior] == 2)
  			return;
  
  		int faceParentage = m_topo_graph.getHalfEdgeFaceParentage(half_edge);
  
  		if ((faceParentage & id_a) != 0 && (faceParentage & id_b) != 0)
  			m_matrix[MatrixPredicate.InteriorInterior] = 2;
  	}
docs: with the interior of area B.