I had some friends with a three-year-old son. For family fun, they liked to play the game Memory. It consisted of a bunch of cards arranged on the floor face down. Those playing took turns, trying to turn over matching pairs of cards. If you got a match, you kept them and went again. The person with the most matches was the winner. As the family played, the dad remarked, "My strategy is that I focus on two or three specific pairs that I’m trying to get, and after I get them, I pick out two or three more." The mother said, "My strategy is that I start on the cards in the
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