Labels:text | screenshot | triangle OCR: D C Figure 2. The Planar Graph theorem, which is due to Kasimir Kuratowski, says that a graph is planar if and only if it has no subgraph in it that can be mapped to the two graphs named K(5) and K(3,3). The K(3,3) graph is shown in Figure 1; the K(5) graph looks like a pentagram,
