The Koenigsberg Bridge problem was conceived by Euler in the 18th century, from proving that a solution does not exist grew what is considered to be the first theorem in Graph Theory. The problem is set in Koenigsberg, Prussia on the Pregel river. Between the two banks of the river there are 2 islands which are connected to the mainland and each other by seven bridges (shown below).

[[Image of puzzle]]

The puzzle is to start at any bridge and walk across each bridge exactly once ending up at your staring point. The puzzle has no solutions and Euler was the first to explain why.

Our aim is to model this problem in Alloy to see if it can find any solutions.

Below is a simplified image if the bridges.