<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "A Tough Nut for Proof Procedures"^^ . "It is well known to be impossible to tile with dominoes a checkerboard with two opposite corners deleted. This fact is readily stated in the first order predicate calculus, but the usual proof which involves a parity and counting argument does not readily translate into predicate calculus. We conjecture that this problem will be very difficult for programmed proof procedures,."^^ . "1964-07" . . . . . . . "John"^^ . "McCarthy"^^ . "John McCarthy"^^ . . . . . . "A Tough Nut for Proof Procedures (Postscript)"^^ . . . . . . "toughnut.ps"^^ . . "HTML Summary of #414 \n\nA Tough Nut for Proof Procedures\n\n" . "text/html" . . . "Artificial Intelligence" . .