The Bridges of Konisburg
The Problem
Konisberg ( now called Kaliningrad) is a city on the Preger River with two islands that were connected to the rest of the city by seven bridges. The river flows around the two islands of the town. The bridges ran from the banks of the river to the islands in the river with a bridge connecting the islands. It became a town tradition to make a Sunday walk, and try to cross each of the seven bridges only once. No one had solved the problem until it came to the attention of the Swiss mathematician Leonhard Euler. At that time, Euler was serving the Russian empress Catherine the Great in St. Petersburg.
Euler Solves the Problem
In the process of solving this problem, Euler launched the branch of mathematics know as topology. He solved the Konisberg Bridge Problem by using an area of topology now known as networks. Using networks, he proved that the problem of crossing each bridge of Konisberg only once was not possible. Euler discovered that if a network had more than 2 odd points, it was not possible to walk it without doubling back. Today, the problem of the bridges of Konisburg is solved by the addition of and eighth bridge.
Leonhard Euler
Leonhard Euler (1707-1783), a Swiss mathematician, became famous for his great output of original mathematics, and for the wide range of subjects he covered. He did much of his work after he became blind in one eye in 1735 and totally blind in 1766.
Euler contributed new ideas in calculus, geometry, algebra, number theory, and probability. He also worked in many areas of applied mathematics, such as acoustics, optics, mechanics, astronomy, artillery, navigation, statistics, and finance. Euler was born in Basel, Switzerland.