Koenigsberg: Bridges of Koenigsberg from Euler's times
In igraphdata: A Collection of Network Data Sets for the 'igraph' Package

The Seven Bridges of Koenigsberg is a notable historical problem in mathematics. Its negative resolution by Leonhard Euler in 1735 laid the foundations of graph theory and presaged the idea of topology.

The city of Koenigsberg in Prussia (now Kaliningrad, Russia) was set on both sides of the Pregel River, and included two large islands which were connected to each other and the mainland by seven bridges

The problem was to find a walk through the city that would cross each bridge once and only once. The islands could not be reached by any route other than the bridges, and every bridge must have been crossed completely every time (one could not walk half way onto the bridge and then turn around and later cross the other half from the other side).

Euler proved that the problem has no solution.

1	Koenigsberg

An undirected igraph graph object with vertex attributes ‘name’ and ‘Euler_letter’, the latter is the notation from Eulers original paper; and edge attributes name (the name of the bridge) and ‘Euler_letter’, again, Euler's notation from his paper.

This dataset is in the public domain.

Wikipedia, http://de.wikipedia.org/wiki/K%C3%B6nigsberger_Br%C3%BCcken

igraphdata documentation built on May 1, 2019, 8:18 p.m.