?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=A+Tough+Nut+for+Proof+Procedures&rft.creator=McCarthy%2C+John&rft.subject=Artificial+Intelligence&rft.description=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%2C+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%2C.&rft.date=1964-07&rft.type=Preprint&rft.type=NonPeerReviewed&rft.format=application%2Fpostscript&rft.identifier=http%3A%2F%2Fcogprints.org%2F414%2F2%2Ftoughnut.ps&rft.identifier=++McCarthy%2C+John++(1964)+A+Tough+Nut+for+Proof+Procedures.++%5BPreprint%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F414%2F