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

On Jun 1, 9:36 pm, G. Frege <nomail@invalid> wrote:
On Fri, 01 Jun 2007 18:26:59 -0000, translogi

<wilem...@xxxxxxxxxxxxxx> wrote:

I bow my head deep you are right,
It was Allan and Hand
~

Ehem... All_e_n. :-)



or even to mention the publication
Logic Primer, 2nd Edition
Colin Allen and Michael Hand
February 2001

I like it very much, I did recomend it to a logic lecturer.
(I don't know if he followed it up.)

I guess the book is ok from a technical point of view. :-)

F.

--

E-mail: info<at>simple-line<dot>de

The only shortcommings (as i see them)
are the ~E rule
(It is anti-intuitionistic, Why not have a bit more proper ~~E rule?
at least smart students will grasp there is something wrong with ~E )

And the way you say that in assumption is decharged, (I like Pospesels
way more)
(an - after the linenumber of the assumption discharged, instead of
putting it after the rule in brackets.)

But these are minor points

The use of DS (disjunctive syllogism) instead of vE is a good thing,
it brings logic back to the Stoic undemonstratebles that also has
DS.


.

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