Chapter 2: Problem 19
For any statements \(p, q\), prove that a) \(\neg(p \downarrow q) \Leftrightarrow(\neg p \uparrow \neg q)\) b) \(\neg(p \uparrow q) \Leftrightarrow(\neg p \downarrow \neg q)\)
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Chapter 2: Problem 19
For any statements \(p, q\), prove that a) \(\neg(p \downarrow q) \Leftrightarrow(\neg p \uparrow \neg q)\) b) \(\neg(p \uparrow q) \Leftrightarrow(\neg p \downarrow \neg q)\)
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Use the substitution rules to verify that each of the following is a tautology. (Here \(p, q\), and \(r\) are primitive statements.) a) \([p \vee(q \wedge r)] \vee \neg[p \vee(q \wedge r)]\) b) \([(p \vee q) \rightarrow r] \leftrightarrow[\neg r \rightarrow \neg(p \vee q)]\) c) \([(p \vee q) \rightarrow r] \vee(s \wedge t)] \leftrightarrow[[(p \vee q) \rightarrow r] \vee s] \wedge[(p \vee q) \rightarrow r] \vee t]]\)
a) For primitive statements \(p, q\), find the dual of the statement \((\neg p \wedge-q) \vee\left(T_{0} \wedge p\right) \vee p\). b) Use the laws of logic to show that your result from part (a) is logically equivalent to \(p \wedge \neg q\).
Let \(p(n), q(n)\) represent the open statements $$ p(n): \quad n \text { is odd } \quad q(n): \quad n^{2} \text { is odd } $$ for the universe of all integers. Which of the following statements are logically equivalent to each other? a) If the square of any integer is odd, then the integer is odd. b) \(\forall n[p(n)\) is necessary for \(q(n)]\) c) The square of any odd integer is odd. d) There are some integers whose squares are odd. e) Given any integer whose square is odd, that integer is likewise odd. f) \(\forall n[\neg p(n) \rightarrow \neg q(n)]\) g) Every integer with an odd square is odd. h) Every integer with an even square is even. i) \(\forall n[p(n)\) is sufficient for \(q(n)]\)
Negate and express each of the following statements in smooth English. a) Kelsey will get a good education if she puts her studies before her interest in cheerleading.
For the following statements the universe comprises all nonzero integers. Determine the truth value of each statement. a) \(\exists x \exists y[x y=1]\) b) \(\exists x \forall y[x y=1]\) c) \(\forall x \exists y[x y=1]\) d) \(\forall x \forall y\left[\sin ^{2} x+\cos ^{2} x=\sin ^{2} y+\cos ^{2} y\right]\) e) \(\exists x \exists y[(2 x+y=5) \wedge(x-3 y=-8)]\) f) \(\exists x \exists y[(3 x-y=7) \wedge(2 x+4 y=3)]\)
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