Write a science joke.

One day, the mathematician felt that he had had enough of mathematics and ran to the fire brigade to announce that he wanted to be a fireman.

The fire chief said, "You look good, but I have to give you a test first."

The fire chief took the mathematician to the backyard alley of the fire brigade. There is a warehouse, a fire hydrant and a hose in the alley.

The fire chief asked, "Suppose the warehouse was on fire, what would you do?"

The mathematician replied, "I connected the fire hydrant to the water pipe, opened the water pipe and put out the fire."

The fire chief said, "Exactly! Last question: suppose you walk into an alley and the warehouse is not on fire, what would you do? "

The mathematician pondered for a long time in doubt and finally replied, "I will set fire to the warehouse."

The fire chief shouted, "What? That's terrible! Why did you set fire to the warehouse? "

The mathematician replied, "In this way, I will simplify the problem into a problem that I have solved."