Answer : A,D
Given :
- f1 → f2 is falsifiable ie for at least one row value (f1,f2) is (T,F).
- f1 → f3 is tautology ie no row value (f1,f3) is (T,F).
- f3 → f1 is invalid ie for at least one row value (f3,f1) is (T,F).
option A : from above 1st point we know at least one row of f2 is False. Therefore, f2 is not tautology.
option B : if f3 is tautology then also all given statements hold.
option C : if f1 is contingency then also all given statements hold.
option D : from above 1st point we know at least one row of f1 is True and from above 2nd point we know when f1 is True, f3 must be True. Thus, we have value for at least one row (f1,f3) as (T,T). Thus, f1 ^ f3 is not contradiction.