# Leonard Euler's Solution to the Konigsberg Bridge Problem - The Fate of Konigsberg

Author(s):
Teo Paoletti

While graph theory boomed after Euler’s solved the Königsberg Bridge problem, the town of Königsberg had a much different fate.  In 1875, the people of Königsberg decided to build a new bridge, between nodes B and C, increasing the number of links of these two landmasses to four.  This meant that only two landmasses had an odd number of links, which gave a rather straightforward solution to the problem.  The creation of the extra bridge may or may not have been subconsciously caused by the desire for a path to solve the town’s famous problem.

However, a new bridge did not solve all of Königsberg's future problems, as the town did not expect back in the nineteenth century, “the sad and war-torn fate that awaited it as host for one of the fiercest battles of WWII.”  During four days in August 1944, British bombers destroyed both the old town and the northern parts of Königsberg.  In January and February 1945, the region surrounding Königsberg is surrounded by Russian forces.  German civilians begin to evacuate from the town, but move too late.  Thousands of people are killed trying to flee by boat and on foot across the icy waters of the Curonian Lagoon.  In April 1945, the Red Army captures Königsberg with about ninety percent of the old town lying in ruins.

A current street map of Königsberg is provided below.  This map shows how much the town has changed.  Many of the bridges were destroyed during the bombings, and the town can no longer ask the same intriguing question they were able to in the eighteenth century.  Along with a greatly different layout, the town of Königsberg has a new name, Kaliningrad, with the river Pregel renamed Pregolya [Hopkins, 6].  While the fate of Königsberg is terrible, the citizens' old coffeehouse problem of traversing each of their old seven bridges exactly one time led to the formation of a completely new branch of mathematics, graph theory.

Teo Paoletti, "Leonard Euler's Solution to the Konigsberg Bridge Problem - The Fate of Konigsberg," Convergence (May 2011)