Polya recommended (among other things) that one break the unsolved problem into smaller problems that are easier to tackle, or try to think of a similar problem which one already knows how to solve. He suggested that, if you are stuck, you should ask: What is the unknown? What are the data? Have I used all the data? Can I draw a diagram? Can I draw up a plan for solving the problem step by step? Can I restate the problem? Can I check the result? Can I work backwards? Can I modify a familiar solution-method to make it suitable for this case? All these heuristics apply to problems outside mathematics — even to casting a play, or designing a dress.
— Boden, Margaret A. The Creative Mind. Myths and Mechanisms. 1990. Second ed. London: Routledge, 2004.
