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March 5th, 2017, 03:47 AM   #1
Joined: Mar 2017
From: london

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Proving logic

Hi everyone, does anyone know what the solutions to these questions would be? I am really struggling with this particular piece of homework, so would appreciate any help or explanations. I have to prove that the following statements are valid in proven logic. Thank you :) (¬ = not → = if/ then)

¬ P → ¬Q: Q → P (6)
: (P →Q) → (¬Q →¬P) (5) Principle of transposition
Q → R : (¬Q →¬P) →(P →R) (9)
(P & Q) →¬R : R →(P →¬Q) (11)
P: [(¬(Q → R) →¬P)] →[( ¬R →¬Q)] (9)
P, ¬Q: ¬ (P →Q) (6)
P, ¬P : Q (8)
: ¬P → (P →Q) (10) Law of Dun Scotus
P → ¬P : ¬P (11)

Last edited by skipjack; March 5th, 2017 at 03:54 AM.
miafuller is offline  
March 5th, 2017, 04:00 AM   #2
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Were you given a list of axioms? If so, what were they? If not, what method of proof were you taught?
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