BiElim

⊢ f ⊃ f BiElim

Proof:

1
⊢ ¬f ⊃¬f
2
⊢ (¬f ⊃ ¬f) ⊃ (¬¬f ⊃ f)
3
⊢ ¬¬f ⊃ f
1, 2,MP
4
⊢ f ⊃ f
3, def. of 

qed

The following is used in the proof of lemma BiImpDist:

2024-08-03
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