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Exercise 5

Avg difficulty 2.5

Simplify the statements below so that negations are only directly next to the predicates.

  1. ¬∃x∀y(¬O(x)∨E(y))\neg \exists x \forall y (\neg O(x) \vee E(y)).
  2. ¬∀x¬∀y¬(x<y∧∃z(x<z∨y<z))\neg \forall x \neg \forall y \neg(x \lt y \wedge \exists z (x \lt z \vee y \lt z)).
  3. There is a number nn for which no other number is either less than or equal to nn.

  4. It is false that for every number nn there are two other numbers which nn is between.

Hammond, Discrete Math for Shockers, §2.3 Propositional Functions and Quantifiers, Exercise 5

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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.