Most recent change of EulerCharacteristic

Edit made on October 26, 2008 by DerekCouzens at 17:07:05

Deleted text in red / Inserted text in green

The Euler Characteristic EQN:\chi was classically defined for polyhedra, according to the formula:


and is equal to 2 on the plane (or sphere) and 0 on the torus.

Using the Euler characteristic we can prove that EQN:K_{3,3} is nonplanar, and hence the classic three utilities problem (from graph theory) has no solution. (see planar graph)