logic of classes

[gh0st]

we know that:


-all x are y
-z are x
-there are no w that are y


so we conclude:
a)z are w?
b)all y are w?
c)all z arent y?
d)x are w?
e)all z are not w?


so my answer was e) but the book says that the answer is d)
 

[p_2001]

actually your question is wrongly posted... there are 2 answers inferred from what you wrote.. c and e are both possible... d is not. afaik.

[gh0st]

actually your question is wrongly posted... there are 2 answers inferred from what you wrote.. c and e are both possible... d is not. afaik.

damn it you confuse me more!! i think the book has a mistake

[p_2001]

see, you said all x.... but not "all z " .. just that "z are x" so that does not mean that all z are x and hence y and consequently not w. z maybe x and some may be w.

[Deque]

so my answer was e)

I would say the same.

c and e are both possible

How is c possible? Can't be.

see, you said all x.... but not "all z " .. just that "z are x" so that does not mean that all z are x

You use the universal quantifier if none is given (not the existential).
The task is just made this way for confusion.

[gh0st]

ty deque you are the best! <3