Theorem bj-biorfi

Description: This should be labeled "biorfi" while the current biorfi should be labeled "biorfri". The dual of biorf is not biantr but iba (and ibar ). So there should also be a "biorfr". (Note that these four statements can actually be strengthened to biconditionals.) (Contributed by BJ, 26-Oct-2019) (Proof modification is discouraged.)

	Ref	Expression
Hypothesis	bj-biorfi.1	⊢ ¬ 𝜑
Assertion	bj-biorfi	⊢ ( 𝜓 ↔ ( 𝜑 ∨ 𝜓 ) )

Proof

Step	Hyp	Ref	Expression
1		bj-biorfi.1	⊢ ¬ 𝜑
2		biorf	⊢ ( ¬ 𝜑 → ( 𝜓 ↔ ( 𝜑 ∨ 𝜓 ) ) )
3	1 2	ax-mp	⊢ ( 𝜓 ↔ ( 𝜑 ∨ 𝜓 ) )