Theorem ifbieq12d2 4582

Description: Equivalence deduction for conditional operators. (Contributed by Thierry Arnoux, 14-Feb-2017.) (Proof shortened by Wolf Lammen, 24-Jun-2021.)

Hypotheses

Ref	Expression
ifbieq12d2.1	⊢ (𝜑 → (𝜓 ↔ 𝜒))
ifbieq12d2.2	⊢ ((𝜑 ∧ 𝜓) → 𝐴 = 𝐶)
ifbieq12d2.3	⊢ ((𝜑 ∧ ¬ 𝜓) → 𝐵 = 𝐷)

Assertion

Ref	Expression
ifbieq12d2	⊢ (𝜑 → if(𝜓, 𝐴, 𝐵) = if(𝜒, 𝐶, 𝐷))

Proof of Theorem ifbieq12d2

Step	Hyp	Ref	Expression
1		ifbieq12d2.2	. . 3 ⊢ ((𝜑 ∧ 𝜓) → 𝐴 = 𝐶)
2		ifbieq12d2.3	. . 3 ⊢ ((𝜑 ∧ ¬ 𝜓) → 𝐵 = 𝐷)
3	1, 2	ifeq12da 4581	. 2 ⊢ (𝜑 → if(𝜓, 𝐴, 𝐵) = if(𝜓, 𝐶, 𝐷))
4		ifbieq12d2.1	. . 3 ⊢ (𝜑 → (𝜓 ↔ 𝜒))
5	4	ifbid 4571	. 2 ⊢ (𝜑 → if(𝜓, 𝐶, 𝐷) = if(𝜒, 𝐶, 𝐷))
6	3, 5	eqtrd 2780	1 ⊢ (𝜑 → if(𝜓, 𝐴, 𝐵) = if(𝜒, 𝐶, 𝐷))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 206   ∧ wa 395   = wceq 1537  ifcif 4548

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1967  ax-7 2007  ax-8 2110  ax-9 2118  ax-ext 2711

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 847  df-tru 1540  df-ex 1778  df-sb 2065  df-clab 2718  df-cleq 2732  df-clel 2819  df-rab 3444  df-v 3490  df-un 3981  df-if 4549

This theorem is referenced by:  ofccat  15018  itgeq12dv  34291  sgnneg  34505