1(a)
(b)
(c)
or equivalently
(d)
Also
(e)
Also
2(a)
(b)
(c) ,
(d)
(e) P
3(a) (1) ,
(2) ,
(3)
(4)
Converse:
(3) If it is snowing, then it is below freezing.
(4) If it is below freezing, then it is snowing.
Neg. (1) If it is not snowing, then it is below freezing.
Neg. (2) If it is snowing, then it is below freezing.
Contrapositive:
(3) If it is not snowing, then it is not below freezing.
(4) If it is not below freezing, then it is not snowing.
Neg. (1) If it is snowing, then it is not below freezing.
Neg. (2) If it is not snowing, then it is not below freezing.
4(a) I: IBN will take over the copier market.
Y: Yerox will take over the copier market.
R: RCB returns to the computer market.
---------------
(b)
-- De Morgan
------------------- by modus ponens
-- Simplification
------------------- by modus ponens
------------------- by modus tollens