Suppose you have a chess program that can evaluate 5 million nodes per second. Decide on a compact representation of a game state for storage in a transposition table. About how many entries can you fit in a 1-gigabyte in-memory table? Will that be enough for the three minutes of search allocated for one move? How many table lookups can you do in the time it would take to do one evaluation? Now suppose the transposition table is stored on disk. About how many evaluations could you do in the time it takes to do one disk seek with standard disk hardware?