To solve
this bridge problem Euler changed the picture into a graph.
This
is the original picture of the problem.
Euler
simplified the picture by labeling the islands A and D and the shores of
the river are B and C. The bridges are a, b, c, d, e, f, and g.
Euler
simplified his graph one more time. In this graph the vertices represent
the land regions and the edges represent the paths over the bridges.





