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Metamath Proof Explorer

Theorem exmidd

Description: Law of excluded middle in a context. (Contributed by Mario Carneiro, 9-Feb-2017)

Ref Expression
Assertion exmidd ( 𝜑 → ( 𝜓 ∨ ¬ 𝜓 ) )

Proof

Step Hyp Ref Expression
1 exmid ⊢ ( 𝜓 ∨ ¬ 𝜓 )
2 1 a1i ⊢ ( 𝜑 → ( 𝜓 ∨ ¬ 𝜓 ) )