I believe therein lies the problem. DeMorgen's was so little touched on in class, and the book that we have does not explain that at all (I have looked). In fact, the book provides plenty of EASY derivations, and leaves the hard ones in the exercises. Of course I am not too proud to admit...
Anyone by chance know of any website where I can find this derivation worked out? I really would like to understand it for a test I have coming up next week. Any help would be greatly appreciated. The only thing I can figure out up to this point is that I must do it with indirect proof.
I believe I will have to go the negation route, as the Law of the Excluded Middle isn't mentioned our book or class (go figure).
I really wish this sort of thing came naturally to me. :/
If someone out there could provide some guidance on this, I would greatly appreciate it! :biggrin:
I am asked to 'proove' that Peirce's Law is a theorem in SD by providing a derivation.
[(A > B)>A]>A
Looks easy, no? Well I am totally :confused: And of course, a search of examples...