1. The problem statement, all variables and given/known data [ (p or r) & (not(p) or r) ] ---> r is a tautology. Prove this without using truth tables. 2. Relevant equations See above. not(p) = !p = p' = the opposite value of p and ---> is an implication. 3. The attempt at a solution I have made some prior simplification, and that is what I have at present. I don't know where to go from here. Expanding the terms seems to make things too complicated. Is there a shorter way? Any help would be greatly appreciated!