oth Given red and blue points in the plane and a planar straight line matching between the red and the blue points, the matching can be extended into a bipartite planar straight line spanning tree. That is, any red-blue planar matching can be completed into a crossing-free red-blue spanning tree. Such a tree can be constructed in time.
['Ferran Hurtado', 'Mikio Kano', 'David Rappaport', 'Csaba D. Tóth']
Encompassing Colored Crossing-Free Geometric Graphs