Theorem 3mix2 601

Description: Introduction in triple disjunction.

Assertion

Ref	Expression
3mix2	⊢ (φ → (ψ ∨ φ ∨ χ))

Proof of Theorem 3mix2

Step	Hyp	Ref	Expression
1		3mix1 600	. 2 ⊢ (φ → (φ ∨ χ ∨ ψ))
2		3orrot 587	. 2 ⊢ ((ψ ∨ φ ∨ χ) ↔ (φ ∨ χ ∨ ψ))
3	1, 2	sylibr 175	1 ⊢ (φ → (ψ ∨ φ ∨ χ))

Syntax hints:   → wi 2   ∨ w3o 580

This theorem is referenced by:  tz7.44-2 2967

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6

This theorem depends on definitions:  df-bi 128  df-or 197  df-3or 582

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