So I understand that quantifiers don’t have contrapositives however I don’t understand the last part of the deduction. If I have Y some X, how is adding on Z not Y some X some Z? How do I determine this on other drills .
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We know that there is at least one XY, and we need to prove that there is at least one ZY.
To prove this, we would need to show that all Xs are Zs.
So we would want
If X - Z or its contrapositive If Not Z - Not X.
Alex-HostonJune 1, 2022
Ok so I understand your explanation however I think I was being more specific to the problem from the drill that I was doing. I think what I'm trying to understand when you have both a conditional statement and a quantifier how do you determine when to use the quantifier and conditional statement together ? For instance, Y some Z>x was the answer but how do we know that it can't be Y some Z some X? How do I study to identify this when I see it again.
