Re: Help with a problem

On Thu, 24 Nov 2005 03:22:21 -0800, William Elliot
<marsh@xxxxxxxxxxxxxxxxxx> wrote:

>
> [...] locating mothers 87 year text book "Essentials of Formal Logic",
> I find some mentions of Modus ponendo tollens [MPT] and Modus tollendo
> ponens [MTP]. [...] Have you see mpt and mtp before?
>
Sure.

Modus ponendo ponens [MPP]
A -> B, A |- B

Modus tollendo tollens [MTT]
A -> B, ~B |- ~A

Modus ponendo tollens [MPT]
~(A & B) & A |- ~B
~(A & B) & B |- ~A

Modus tollendo ponens [MTP]
A v B, ~A |- B
A v B, ~B |- A

Source:
J. E. Lemmon, Beginning Logic.


F.

--
"I do tend to feel Hughes & Cresswell is a more authoritative
source than you." (D. Ullrich)
.