“There is a well-known joke—at least well known in mathematics—about how mathematicians work. A mathematician and a Starbucks barista are each placed in front of a stove with a kettle and a nearby faucet and told to make boiling water. Both do the same thing. They fill the kettle with water from the faucet, light the stove with a match, and place the water-filled kettle on the stove. Mission accomplished. The mathematician and the Starbucks barista are next placed in front of a stove with a kettle that they are told is filled with clean water and told to make boiling water yet again. The barista lifts the kettle off the stove for a moment, lights the stove, and puts the kettle back on. The mathematician lifts the kettle off the stove, pours out the water into a sink, puts the newly emptied kettle back on the stove and says, “The problem has been reduced to the previously solved case. Q.E.D.”