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Logical Expressions and Negations in Discrete Mathematics

snhu MODULE ONE PROBLEM SET This document is proprietary to Southern New Hampshire University. It and the problems within may not be posted on any non-SNHU website. Thomas Bagnardi 1 snhu Directions: Type your solutions into this document and be sure to show all steps for arriving at your solution. Just giving a final number may not receive full credit. PROBLEM 1 In the following question, the domain of discourse is a set of male patients in a clinical study. Define the following predicates: · P(x) : x was given the placebo · D(x) : x was given the medication · M(x) : « had migraines Translate each of the following statements into a logical expression. Then negate the expression by adding a negation operation to the beginning of the expression. Apply De Morgan's law until each negation operation applies directly to a predicate and then translate the logical expression back into English. Sample question: Some patient was given the placebo and the medication. . Ex (P(x) A D(x)) . Negation: - 3x (P(x) \ D(x)) . Applying De Morgan's law: Vx (-P(x) V -D(x)) · English: Every patient was either not given the placebo or not given the medication (or both). snhu (a) Every patient was given the medication or the placebo or both. • forallx (D(x) V P(x)) · Negation: - Vx (D(x) V P(x)) · Applying De Morgan's law: 3x (-D(x) A -P(x)) · English: There is a patient who was not given the medication and not given the placebo. (b) Every patient who took the placebo had migraines. (Hint: you will need to apply the conditional identity, p -> q = p V q.) . Vx (P(x) -> M(x)) · Negation: - Vx (P(x) -> M(x)) · Applying Conditional Identity: (P(x) > M(x) = (-P(x) V -M(x) · Applying Double Negation: - P(x) = P(x) . Applying De Morgan's law: 3x (P(x) A -M(x)) · English: Some patient took the placebo and did not have migraines. (c) There is a patient who had migraines and was given the placebo. . Ex (M(x) \ P(x)) . Negation: - 3x (M(x) \ P(x)) . Applying De Morgan's law: Vx (-M(x) V -P(x)) · English: Every patient did not have migraines or did not take the placebo.