11.     Duchamp's use of the fourth dimension as an unconscious mental process is metaphorical. Massive amounts of information and patterns, beyond what the physical eyes or conscious mind can see or know, are clearly utilized in professional chess: 64 squares and 32 chess pieces have vast potential combinations-169, 518, 829, 100, 544, quintillion in the first 10 moves alone-a number of choices beyond conscious 3-D thought and constituting what Duchamp defined as 4-D.