Discrete Mathematics and Its Applications, Seventh Edition

Published by McGraw-Hill Education
ISBN 10: 0073383090
ISBN 13: 978-0-07338-309-5

Chapter 1 - Section 1.8 - Proof Methods and Strategy - Review Questions - Page 111: 6

Answer

Universal and Existential Quantification $ \exists x P(x)$: There exists an element $x$ iin the domain such that $\ P(x)$. Universal Quantitfication $\forall x P(x) $ : $P(x) $ for all values of $x$ in the domain. $\neg \exists x P(x) \equiv \forall x \neg P(x)$ $\neg \forall x P(x) \equiv \exists x \neg P(x)$

Work Step by Step

Universal and Existential Quantification $ \exists x P(x)$: There exists an element $x$ iin the domain such that $\ P(x)$. Universal Quantitfication $\forall x P(x) $ : $P(x) $ for all values of $x$ in the domain. Negation: $¬p$: not $p$ The negation thus adds the symbol ¬ in front of the expression: $\neg \exists x P(x)$ $\neg \forall x P(x)$ These statements are also logically equivalent with th following statements using De Morgans laws for Qualifiers: $\neg \exists x P(x) \equiv \forall x \neg P(x)$ $\neg \forall x P(x) \equiv \exists x \neg P(x)$
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