 QUESTION

# Choose one of the proofs below and use one of the indirect proof techniques (reductio ad absurdum or conditional proof) presented in Chapter 8 to...

Choose one of the proofs below and use one of the indirect proof techniques (reductio ad absurdum or conditional proof) presented in Chapter 8 to demonstrate the validity of the argument. The proofs below may use any of the rules of inference or replacement rules given in Chapter 8.

1. (G • P) → K, E → Z, ~P → ~ Z, G → (E v L), therefore, (G • ~L) → K
2. (S v T) v E, S → (F • ~G), A → W, T → ~W, therefore, (~E • A) → ~G
3. (S v T) v (U v W), therefore, (U v T) v (S v W)
4. ~Q → (L → F), Q → ~A, F → B, L, therefore, ~A v B
5. ~S → (F → L), F → (L → P), therefore, ~S → (F → P)

In mathematics, it is very common for there to be multiple ways to solve a given a problem; the same can be said of logic. There is often a variety of ways to perform a natural deduction. In your peer responses, make suggestions for an alternate proof. Consider the following questions when constructing your response:

If the proof was done using RAA, could it be done using CP? What about vice versa?

Will a direct proof work for any of these?

Can the proof be performed more efficiently by using different equivalence rules?