Discrete Mathematics with Applications 4th Edition

Published by Cengage Learning
ISBN 10: 0-49539-132-8
ISBN 13: 978-0-49539-132-6

Chapter 3 - The Logic of Quantified Statements - Exercise Set 3.2 - Page 117: 48

Answer

No. Interpreted formally, the statement says, “If carriers do not offer the same lowest fare, then you may not select among them,” or, equivalently, “If you may select among carriers, then they offer the same lowest fare.” “If carriers do not offer the same lowest fare, then you may not select among them,” is the inverse statement of "If two carriers offer the same lowest fare, then the customer will be free to choose between them." The two statements are not logically equivalent.

Work Step by Step

Recall the definition of only if: "$\forall x$, r(x) only if s(x)" means "$\forall x$, if ~s(x) then ~r(x)" or equivalently "$\forall x$, if r(x) then s(x). Recall also the definition of inverse of a statement: A statement of the form: $\forall x \in D$, if P(x) then Q(x), and as its inverse statement: $\forall x \in D$, if ~P(x) then ~Q(x)." The inverse is not logically equivalent to the original statement.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.