How to prove Distractive dilemma ?

[phydis]

[ [(p-->q) and (r-->s)] and (~q or ~s) ] --> (~p or ~r)

I know all basic theories in Logic and I want to know the correct way/correct steps of proving this kind of things? I'm a beginner.. please help

I can explain above dilemma in words, but I have no idea how to write down the proof correctly.

 

[Stephen Tashi]

I have no idea how to write down the proof correctly.

There isn't a single standard for doing proofs that is correct. In a logic course, you would be given certain permissible patterns to use in a proof and you would naturally be expected to use them. (It's also taught in logic courses that proofs can be done by using truth tables.) If this problem arose in a discussion in a calculus course, it would probably be acceptable to offer a proof in words. You have to explain in what context you wish to give a proof.

Also, I don't think the names of proof techniques used in logic books are completely standardized, so a person might have to be familiar with the book or materials you are using in order to advise you.

 

[verty]

Proving it by contradiction may be the easiest way. See if you can do that.