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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 
|- ( ph -> ( ps \/ -. ps ) )

Proof

Step Hyp Ref Expression
1 exmid 
 |-  ( ps \/ -. ps )
2 1 a1i 
 |-  ( ph -> ( ps \/ -. ps ) )