Re: Help with a problem


Torkel Franzen wrote:
>
> In intuitionistic logic, there is no distinction between direct
> and indirect proofs, since there are no indirect proofs. It is in
> classical logic and mathematics that the distinction is significant.

Well, don't keep us in suspense. What exactly is the distinction
you're making between:
(1) "concluding ~A from a derivation of a contradiction from A"
and
(2) "concluding A from a derivation of a contradiction from ~A".

And why do you see it as significant?

.

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