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Metamath Proof Explorer

Theorem pm4.45

Description: Theorem *4.45 of WhiteheadRussell p. 119. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm4.45 ⊢ φ ↔ φ ∧ φ ∨ ψ

Proof

Step Hyp Ref Expression
1 orc ⊢ φ → φ ∨ ψ
2 1 pm4.71i ⊢ φ ↔ φ ∧ φ ∨ ψ