Welcome to SWI-Prolog (Multi-threaded, 64 bits, Version 6.6.6) Copyright (c) 1990-2013 University of Amsterdam, VU Amsterdam SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions. Please visit http://www.swi-prolog.org for details. For help, use ?- help(Topic). or ?- apropos(Word). X = 7, L = [7, 7], L5 = [[7, 7], [7, 7], [7, 7], [7, 7], [7, 7]]. % halt