A conditional proof corresponds to the application of what Douglas Hofstadter calls the "Fantasy Rule" in his masterwork "GEB:EGB". Surprisingly, the theory of propositional calculus which he develops in GEB:EGB employs several inference rules but no ______: the need for any ______ is done away with through application of the Fantasy Rule.
문제 2 :
The system, which has come to be known as IZF, or Intuitionistic Zermelo–Fraenkel (ZF refers to ZFC without the _____ of choice), has the usual axioms of extensionality, pairing, union, infinity, separation and power set. The _____ of regularity is stated in the form of an _____ schema of set induction. Also, while Myhill used the _____ schema of replacement in his system, IZF usually stands for the version with collection.WP