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CS 486 Applied Logic Assignment #3
Spring 1997 Due Date: Thurs., 2/13/97

Reading: Smullyan Chapter IV for Thurs.

  1. Complete the argument sketched in class that any formula provable by Tableau can be proved in the single-goal Refinement Logic with Magic and Cut.
  2. Prove Pierce's law, , in Refinement Logic (you will need , and Cut will help).
  3. Describe how to apply the Tableau-to-Hilbert transformation to prove Pierce's law) in the Hilbert system using axiom as well as , and also this axiom . Carry out the step of proving Pierce's law and the step of showing a Hilbert proof of Pierce's law from the assumption of .

    This transformation does not prove Pierce's law from the three axioms of assignment 2 (called ), but it will give you insight into the role of the third axiom if you recall that we can define as .

    Note, for your information, it is possible to convert your proof into a proof, so this will show you what is involved in finding a proof in assignment 2. are the axioms in assignment 2.

  4. Solve the exercise in Smullyan p.36.



cs486@cs.cornell.edu
Mon Feb 17 08:15:25 EST 1997