(a) Do there exists propositions P,Q such that both P → Q and its converse are true? (b) Do there exist propositions P,Q such that both P » Q and its converse are false? Justify your answers by giving an example or a proof that no such examples exist.

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Use the rules of inference and the laws of propositional logic to prove that each argument is valid. Number each line of your argument and label each line of your proof "Hypothesis" or with the name of the rule of inference used at that line. If a rule of inference is used, then include the numbers of the previous lines to which the rule is applied. 비 (c) (d) D EXERCISE 1.12.2: Proving arguments are valid using rules of inference. → P→ (q^r) -q -P (p^q) →r -r 9 :-P (pvq) →r p Ar pvq -pvr -q p→q r-u par q^u Feedback?