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Metamath Proof Explorer

Theorem 3mix3

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

Ref Expression
Assertion 3mix3 ⊢ φ → ψ ∨ χ ∨ φ

Proof

Step Hyp Ref Expression
1 3mix1 ⊢ φ → φ ∨ ψ ∨ χ
2 3orrot ⊢ φ ∨ ψ ∨ χ ↔ ψ ∨ χ ∨ φ
3 1 2 sylib ⊢ φ → ψ ∨ χ ∨ φ