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Metamath Proof Explorer

Theorem 3mix1

Description: Introduction in triple disjunction. (Contributed by NM, 4-Apr-1995)

Ref Expression
Assertion 3mix1 ⊢ φ → φ ∨ ψ ∨ χ

Proof

Step Hyp Ref Expression
1 orc ⊢ φ → φ ∨ ψ ∨ χ
2 3orass ⊢ φ ∨ ψ ∨ χ ↔ φ ∨ ψ ∨ χ
3 1 2 sylibr ⊢ φ → φ ∨ ψ ∨ χ