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Chapter Review

Mixed practice over equivalences, quantified statements, set identities and short written proofs, with no cue about which technique applies.

Discrete Math for Shockers, Chapter Review

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8 exercises

Exercise 1

Complete a truth table for the statement ¬p→(q∧r)\neg p \to (q \wedge r).

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Exercise 3

Are the statements p→(q∨r)p \to (q \vee r) and (p→q)∨(p→r)(p \to q) \vee (p \to r) logically equivalent? Explain your answer.

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Exercise 4

Is the following a valid deduction rule? Explain.

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Exercise 5

Write the negation, converse and contrapositive for each of the statements below.

  1. If the power goes off, then the food will spoil.

  2. If the door is closed, then the light is off.

  3. ∀x(x<1→x2<1)\forall x (x \lt 1 \to x^2 \lt 1).
  4. For all natural numbers nn, if nn is prime, then nn is solitary.

  5. For all functions ff, if ff is differentiable, then ff is continuous.

  6. For all integers aa and bb, if a⋅ba\cdot b is even, then aa and bb are even.

  7. For every integer xx and every integ…

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Exercise 6

Consider the statement: for all integers nn, if nn is even and n≤7n \le 7 then nn is negative or n∈{0,2,4,6}n \in \{0,2,4,6\}.

  1. Is the statement true? Explain why.

  2. Write the negation of the statement. Is it true? Explain.

  3. State the contrapositive of the statement. Is it true? Explain.

  4. State the converse of the statement. Is it true? Explain.

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Exercise 7

Consider the statement: ∀x(∀y(x+y=y)→∀z(x⋅z=0))\forall x (\forall y (x + y = y) \to \forall z (x\cdot z = 0)).

  1. Explain what the statement says in words. Is this statement true? Be sure to state what you are taking the universe of discourse to be.

  2. Write the converse of the statement, both in words and in symbols. Is the converse true?

  3. Write the contrapositive of the statement, both in words and in symbols. Is the contrapositive true?

  4. Write the negation of the statement, both in words…

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Exercise 8

Write each of the following statements in the form, “if …, then ….” Careful, some of the statements might be false (which is alright for the purposes of this question).

  1. To lose weight, you must exercise.

  2. To lose weight, all you need to do is exercise.

  3. Every American is patriotic.

  4. You are patriotic only if you are American.

  5. The set of rational numbers is a subset of the real numbers.

  6. A number is prime if…

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Exercise 9

Simplify the following.

  1. ¬(¬(p∧¬q)→¬(¬r∨¬(p→r)))\neg (\neg (p \wedge \neg q) \to \neg(\neg r \vee \neg(p \to r))).
  2. ¬∃x¬∀y¬∃z(z=x+y→∃w(x−y=w))\neg \exists x \neg \forall y \neg \exists z (z = x + y \to \exists w (x - y = w)).
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Adapted from Discrete Math for Shockers © 2021 John Hammond. Licensed under CC BY-SA 4.0. Source: Discrete Math for Shockers. Imported at revision 2538beb.