Question 973154
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Prove by exhaustive cases:


Since P v R is given, the case P and case R are exhaustive.


Assume P.  Then P v Q by Disjunction Introduction.


Assume R.  Then Q from R -> Q by Modus Ponens and then P v Q by Disjuction Introduction.


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it

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*[tex \LARGE \ \ \ \ \ \ \ \ \ \