Hi

I have to prove a simple proposition. But I am getting some problems

Now I can do this using truth tables. But I wanted to do it little differently. We can express disjunction as an implication.

since this is an implication, we can assume , so the goal is to prove . But this itself is an implication, so we can further assume , and so the goal is . So our givens are

and the goal is . Now the givens give us

So we get our goal, . But I am also getting and . So I am little confused here.......