Posted by **Abby** on Thursday, May 10, 2007 at 11:41pm.

I need help constructing a formal proof of validity for the following:

1. B<->(L•D), ~D, so ~B

2. R v (S•~T), (R v S) -> (U v ~T), so T->U

3. A -> ([E•~G) ->M], ~ (~E v G) -> (M -> F), so A -> [~ (~G -> ~E) ->F