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Metamath Proof Explorer

Theorem pm2.07

Description: Theorem *2.07 of WhiteheadRussell p. 101. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.07 ⊢ φ → φ ∨ φ

Proof

Step Hyp Ref Expression
1 olc ⊢ φ → φ ∨ φ