A STROLL THROUGH KÖNIGSBERG
In order to place Euler’s formula in a modern context, we must discuss a mathematical field called graph theory. This is not the study of graphs of functions that we encountered in high school precalculus (y = mx + b is a line, y = x2 is a parabola, and so on.). It is the study of graphs such as those shown in figure 11.1. They are made of points, called vertices, and lines joining these points, called edges.*
In 1736, during his first stay in St. Petersburg, Euler tackled the now famous problem of the seven bridges of Königsberg. ...