Theorem imbibiOLD 395

Description: Obsolete version of imbibi 394 as of 15-Jun-2026. The antecedent of one side of a biconditional can be moved out of the biconditional to become the antecedent of the remaining biconditional. (Contributed by BJ, 1-Jan-2025.) (Proof shortened by Wolf Lammen, 5-Jan-2025.) (New usage is discouraged.) (Proof modification is discouraged.)

Assertion

Ref	Expression
imbibiOLD	⊢ (((𝜑 → 𝜓) ↔ 𝜒) → (𝜑 → (𝜓 ↔ 𝜒)))

Proof of Theorem imbibiOLD

Step	Hyp	Ref	Expression
1		pm5.4 391	. . 3 ⊢ ((𝜑 → (𝜑 → 𝜓)) ↔ (𝜑 → 𝜓))
2		imbi2 350	. . 3 ⊢ (((𝜑 → 𝜓) ↔ 𝜒) → ((𝜑 → (𝜑 → 𝜓)) ↔ (𝜑 → 𝜒)))
3	1, 2	bitr3id 287	. 2 ⊢ (((𝜑 → 𝜓) ↔ 𝜒) → ((𝜑 → 𝜓) ↔ (𝜑 → 𝜒)))
4	3	pm5.74rd 276	1 ⊢ (((𝜑 → 𝜓) ↔ 𝜒) → (𝜑 → (𝜓 ↔ 𝜒)))

Syntax hints:   → wi 4   ↔ wb 208

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 209

This theorem is referenced by: (None)