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Step * 1 of Lemma classical-excluded-middle


1. P : ℙ@i'
⊢ {P ∨ (¬P)}
BY
{ (DoubleNegateClassical THENA Auto) }

1
1. P : ℙ@i'
2. P ∨ (¬P) ∈ ℙ
⊢ ¬¬(P ∨ (¬P))

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Latex:

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Latex:

1.  P  :  \mBbbP{}@i'
\mvdash{}  \{P  \mvee{}  (\mneg{}P)\}


By

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Latex:
(DoubleNegateClassical  THENA  Auto)

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