thinks about it in a world of "all possible moves," and it makes a big tree for all of those moves, like this: In this tree, there are 20 possible moves for white. There are 20 * 20 = 400 possible moves for black, depending on what white does. Then there are 400 * 20 = 8,000 for white. Then there are 8,000 * 20 = 160,000 for black, and so Venus dial up services, Venus, PA up services dial VenusVenus up services, dial Pennsylvania, Venus dial up services
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