#Proof writing question

14 messages · Page 1 of 1 (latest)

proud thicket
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I have P∨Q, P->A and ¬Q and I want to proof A.
I divided the PvQ into cases.
Case 1: P, since P->A, so A.
Case 2: Q, but it contradicted with ¬Q, so this case is impossible.
Since case 1 alone already exhausted all possible cases, I concluded that A.
Is this proof fine?

sinful adderBOT
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versed dirge
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since you have (P or Q) and -Q, you must have P

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cases are not necessary, show that P and apply modus ponens as you did

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@proud thicket

proud thicket
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okay got it

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i thought when i see or i must use cases

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sry for late reply

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thank you so much

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+close

rancid oarBOT
# proud thicket +close
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rancid oarBOT
# rancid oar

Thank you for your feedback! aL has been awarded 1 helper_points. They now have 852 helper_points. They have 2 helper_points daily left for today.

rancid oarBOT
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@proud thicket

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