Theorem bi23imp1 45422

Description: Similar to 3imp 1128 except all but outermost implication are biconditionals. (Contributed by Alan Sare, 6-Nov-2017.)

Hypothesis

Ref	Expression
bi23imp1.1	⊢ (𝜑 → (𝜓 ↔ (𝜒 ↔ 𝜃)))

Assertion

Ref	Expression
bi23imp1	⊢ ((𝜑 ∧ 𝜓 ∧ 𝜒) → 𝜃)

Proof of Theorem bi23imp1

Step	Hyp	Ref	Expression
1		bi23imp1.1	. . 3 ⊢ (𝜑 → (𝜓 ↔ (𝜒 ↔ 𝜃)))
2		biimp 218	. . 3 ⊢ ((𝜒 ↔ 𝜃) → (𝜒 → 𝜃))
3	1, 2	biimtrdi 256	. 2 ⊢ (𝜑 → (𝜓 → (𝜒 → 𝜃)))
4	3	3imp 1128	1 ⊢ ((𝜑 ∧ 𝜓 ∧ 𝜒) → 𝜃)

This proof depends on syntax axioms:   → wi 4   ↔ wb 209   ∧ w3a 1103

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 210  df-an 402  df-3an 1105

This theorem is used by: (None)