Identify what you can properly conclude from the given premises: P: not A → B P: A → not Z P: not Z → F C: ?

Natalie June 28, 2016

A and B are correct answers

for A answer: notA->B->Z->notF Therefore, B-> notF is true for B answer: notB->A->notZ->F Therefore, notB->F is true

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Mehran July 2, 2016

@Natalie that is not correct.

The correct transitive chain here is created as follows:

not B ==> A ==> not Z ==> F

not B ==> F

The contrapositive of this chain is:

not F ==> Z ==> not A ==> B

not F ==> B

(A) is the negation of transitive conclusion not B ==> F but you cannot just negate.

The contrapositive is created by reversing AND negating.

Hope this helps! Please let us know if you have any other questions.