March 5th, 2017, 04:47 AM  #1 
Newbie Joined: Mar 2017 From: london Posts: 2 Thanks: 0  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 04:54 AM. 
March 5th, 2017, 05:00 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 16,936 Thanks: 1253 
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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logic, proving 
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