Euler developed the mathematical discipline called graph theory.Did you know that graph theory is a surprisingly important part of our life. Do you know where we use graph theory now, even though Euler invented it over 250 years ago?

Just last week my kids were trying to solve a math problem. Their teachers had given them the graph on the right and asked them to try and draw it without lifting their pencil, and without tracing over any line multiple times:

You might notice that this graph is EXACTLY the graph related to the Knigsberg Bridge problem (on the left). The dots on the right are the land masses, and the lines connecting the dots are the bridges. They were surprised that I knew how to solve the problem (i.e. that it was not solvable) and also that this had anything to do with math.

So where else do we use graph theory?