As an experiment, an engineer, a physicist and a mathematician were locked into separate rooms. In each room was a sealed can of food. After a day, the rooms were opened.

In the first room, they found the engineer, asleep and snoring, with the empty can next to him. When questioned, he said that he had beaten the can to find its pressure point.

In the second room, they found the physicist, studying the empty can and reciting scientific formulas. He said he had derived the solution for opening the can.

In the third room, the mathematician was found, staring at the can and mumbling, "Assume the can is open, assume the can is open ... "