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Text File  |  1992-11-05  |  1.1 KB  |  23 lines
  1. Newsgroups: sci.logic
  2. Path: sparky!uunet!stanford.edu!CSD-NewsHost.Stanford.EDU!Sunburn.Stanford.EDU!pratt
  3. From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
  4. Subject: Re: Impredicativity - was: Russell's Paradox
  5. Message-ID: <1992Nov5.174527.22908@CSD-NewsHost.Stanford.EDU>
  6. Sender: news@CSD-NewsHost.Stanford.EDU
  7. Organization: Computer Science Department,  Stanford University.
  8. References: <Bx693z.H37@cantua.canterbury.ac.nz> <1992Nov4.073717.22625@CSD-NewsHost.Stanford.EDU> <1992Nov5.164251.29649@guinness.idbsu.edu>
  9. Date: Thu, 5 Nov 1992 17:45:27 GMT
  10. Lines: 11
  11.  
  12. In article <1992Nov5.164251.29649@guinness.idbsu.edu> holmes@garnet.idbsu.edu (Randall Holmes) writes:
  13. >You do not "weaken" FA to AFA; ZFC- + FA and ZFC- + AFA are both
  14. >stronger than ZFC-, but neither is stronger than the other.
  15.  
  16. I guess this must be another of my misconceptions.  My general
  17. impresssion was that AFA was automatically true under FA, by virtue of
  18. the latter saying that only "unwound" graphs were permitted, and that
  19. every chain on the unwinding had to terminate.  So what's an example FA
  20. situation contradicting AFA?
  21. -- 
  22. Vaughan Pratt                There's no truth in logic, son.
  23.