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Understand logical implication in statement equivalence by proving the relationship between statements using logical symbols and truth tables. Learn how to show logical equivalence and implications between statements.
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Definition • Let p and q be any two statements, p implies q if and only if p v q Ξ q • aka p implies q if the statement “p or q” is logically equivalent to the statement q • p q is read “p implies q” • p q is read “p does not imply q”
Examples • p: the animal is a beagle • q: the animal is a dog • We can say p q bc The animal is a beagle or the animal is a dog is logically equivalent to The animal is a dog
Prove this relationship [(p q) ^ ~q ] ~ p To prove this we need to show [(p q) ^ ~q ] v ~ p Ξ ~ p WHY????? p implies q if and only if p v q Ξ q
SO LETS PROVE IT [(p q) ^ ~q ] v ~ p Ξ ~ p
Prove another [(p ~q) ^ q ] q
HOMEWORK 5 Use a truth table to prove [ (p q) ^ p ] q