Re: Answer "how to prove ~(P <--> Q) |- ~P <-->Q "

On Jun 1, 10:37 pm, herbzet <herb...@xxxxxxxxx> wrote:
"Jesse F. Hughes" wrote:
herbzet writes:
My copy doesn't have CP. What is CP?

Conditional proof (sometimes called -> intro).

Assume P. Derive Q. Conclude P -> Q.

Thank you.



IIRC, the system Copi used in the first edition of his book on prop
logic didn't have a CP rule, and was proven to be incomplete. He used
a different rule set in the second edition.


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