Solution to 4.

 

4. Use a truth table to answer the following questions about the following 4 statements.

a) Are 1-2 consistent with 3?
b) Do any of 1-2 individually imply 3?
c) Do 1-2 jointly imply 3?

1.x&~z

2.zv(x->~x)

3.y->(x->z)

 
 x  y  z  ~x  ~z  x->~x  (x->z)  x&~z  zv(x->~x)  y->(x->z)
 T  T  T  F  F  F  T  F  T  T
 T  T  F  F  T  F  F  T  F  F
 T  F  T  F  F  F  T  F  T  T
 T  F  F  F  T  F  F  T  F  T
 F  T  T  T  F  T  T  F  T  T
 F  T  F  T  T  T  T  F  T  T
 F  F  T  T  F  T  T  F  T  T
 F  F  F  T  T  T  T  F  T  T

a) Are 1-2 consistent with 3?

No. There is no row on which all statements are true.

b) Do any of 1-2 individually imply 3?

1 does not imply 3, as can be seen by the second row where 1 is T and 3 is F.
2 does imply 3, as can be seen by the fact that there is no row on which 2 is T while 3 is F.

c) Do 1-2 jointly imply 3?

Yes. As can be seen by the fact that there is no row on which 1 and 2 are T while 3 is F.