匈牙利著名的数学家罗莎·彼得在他的名著《无穷的玩艺》中有一个十分生动而有趣的笑话:有人向一群人提出了这样一个问题:“假设在你面前有煤气灶、水龙头、水壶和火柴,你想烧开水,应当怎样去做?”对此某人回答:“在壶中灌上水,点燃煤气,再把壶放到煤气灶上.”提问者肯定了这一回答,但是,他又追问道:“如果其他的条件都没有变化,只是水壶中已经有了足够多的水,那么你又应该怎么做?”这时,“灵活” The famous Hungarian mathematician Rosa Peter has a very vivid and funny joke in his famous book Infinity: Someone raised the question to a group of people: “Suppose you have a gas cooker, a faucet in front of you , Kettle and match, what should you do when you want to boil water? ”“ Someone else replied: ”Fill the kettle with water, light the gas, and place the kettle on the gas cooker.“ This answer, however, he pursued: ”If there is no change in other conditions, but there is already enough water in the kettle, then what should you do?“ ”At this moment,“ flexible ”