Question: In an article generally acknowledged to be one of the origins of the graph theory 7 Leonhard Euler (pronounced Oiler) described a geographic problem that he offered as an elementary example of what he called "the geometry of position." The problem, known as the "K¨onigsberg Bridge Problem," concerns the town of K¨onigsberg in Prussia (now Kaliningrad in Russia), which is shown in a schematic map (circa 1700) in Figure. Euler tells us that the citizens amused themselves by trying to find a walk through town that crossed each of the seven bridges once and only once (and, hopefully, ended where it started). Is such a walk possible?
