Hi all!
So I need some clarifications...! Please help!
Contrapositive for "some" doesn't exist because it's reversible.
A (-s-) /B (Some A are not B) = /B (-s-)A (Some not B are A)
Right?
Then why do we have contrapositive for "if and only if" even though it's reversible? A (-) B = /A (-) /B
I know that A (-) B = A -> B + B -> A, so the contrapositive has to be /B -> /A + /A -> /B.
So my questions are as follows:
(1) Since the reasoning proves that contrapositive exists, does that mean that "Contrapositive for "some" doesn't exist because it's reversible" is wrong?
(2) When I am taking the contrapositive A (-) B (= A -> B AND B -> A), I say /A (-) /B because /B -> /A AND /A -> /B. In this case, why don't I change And to Or? I know I did the contrapositive, but I am starting to get confused...!
Thank you so much in advance!!!