However, the main source of inspiration for planar graphs was the Four Color Conjecture (now Theorem; cf. Chapter 8) that the vertices of any planar graph can be colored with four colors in such a way ...

A classic example, the Four Colour Theorem, illustrates a fundamental property of planar graphs, while recent advancements have extended these ideas to more specialised variants, including list ...

GCSE OCR Solving 'graphical' problems - OCR Example 3- Distance-time graphs Graphical problems will usually be linked to a real-life situation. Travel graphs, temperature graphs and conversion ...

Example - distance graph The distance graph shows the height of a plane as it completes a journey.

If G is a planar graph, we may add edges to construct a maximal planar graph H containing G, so that H triangulates the sphere. If G is toroidal, then by adding edges we can extend G to a maximal ...