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Metamath Proof Explorer

Theorem pm2.26

Description: Theorem *2.26 of WhiteheadRussell p. 104. See pm2.27 . (Contributed by NM, 3-Jan-2005) (Proof shortened by Wolf Lammen, 23-Nov-2012)

Ref Expression
Assertion pm2.26 
|- ( -. ph \/ ( ( ph -> ps ) -> ps ) )

Proof

Step Hyp Ref Expression
1 pm2.27 
 |-  ( ph -> ( ( ph -> ps ) -> ps ) )
2 1 imori 
 |-  ( -. ph \/ ( ( ph -> ps ) -> ps ) )