laws of proposition: prove p V r -> q = ~p

[solomon_13000]

p V r -> q = ~p

my solution:

~(p V r) V q

(~p /\ ~r) V q

~(~p /\ ~r) -> q

~q -> (~p /\ ~r)

I tried the above but I still cant proof that p V r -> q = ~p.

Is my steps correct.

 

[pka]

p V r -> q = ~p

That is not valid!
If p=F , r=T & q=F then [(pVr)->q]=F but [~p]=T.

Did you post the correct problem?

 

[solomon_13000]

This is the problem im trying to solve:

State the rules of inference (or/and laws of proposition) used for each step in the following proofs:

a) p V r -> q, ~s, q -> s alpha ~p

1. p V r -> q Premise 1
2. ~s Premise 2
3. q -> s Premise 3
4. p V r -> s 1, 3
5. ~(p /\ r) 2, 4
6. ~p /\ ~r 5
7. ~p 6

OR

1. p V r -> q Premise 1
2. ~s Premise 2
3. q -> s Premise 3
4. ~q
5. ~(p V r)
6. ~p /\ ~r
7. ~p