Propositional calculus - I can't get why the answer for this test question is what it is Consider the following premises.


*

*If A = B then B = C.

*B != C.

*If C > D then D < E.

*F != G and A = B.

*A = B or C > D.


Alternatives:
a) F != G
b) F != G and D < E
c) A = B
d) B = C or D < E
e) D < E
The answer sheet says the correct alternative is B.
I am confused, because (1) and (2) seems to imply that A != B. In which case (4) would be contradictory. That's why I am wondering if the question itself is wrong.

You are right; the question is wrong. From (4) we get A = B, and then by (1) we get B = C, contradicting (2).
