The Seven Bridges of Königsberg

The Seven Bridges of Königsberg is a famous problem in mathematics and graph theory. It involves a city with seven bridges connecting different landmasses. The challenge was to determine whether one could walk through the city crossing each bridge exactly once without retracing steps. Mathematicians, including Leonhard Euler, proved that such a route is impossible because of the way the landmasses are connected—specifically, because most land areas have an odd number of bridges leading to them. This insight laid the foundation for modern graph theory, helping us understand complex networks in transportation, communication, and more.