elrab2 - Intuitionistic Logic Explorer

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Theorem elrab2 2751

Description: Membership in a class abstraction, using implicit substitution. (Contributed by NM, 2-Nov-2006.)

**Hypotheses**
Ref	Expression
elrab2.1	⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓))
elrab2.2	⊢ 𝐶 = {𝑥 ∈ 𝐵 ∣ 𝜑}

**Assertion**
Ref	Expression
elrab2	⊢ (𝐴 ∈ 𝐶 ↔ (𝐴 ∈ 𝐵 ∧ 𝜓))

Distinct variable groups: 𝜓,𝑥 𝑥,𝐴 𝑥,𝐵 Allowed substitution hints: 𝜑(𝑥) 𝐶(𝑥)

**Proof of Theorem elrab2**
Step	Hyp	Ref	Expression
1		elrab2.2	. . 3 ⊢ 𝐶 = {𝑥 ∈ 𝐵 ∣ 𝜑}
2	1	eleq2i 2145	. 2 ⊢ (𝐴 ∈ 𝐶 ↔ 𝐴 ∈ {𝑥 ∈ 𝐵 ∣ 𝜑})
3		elrab2.1	. . 3 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓))
4	3	elrab 2749	. 2 ⊢ (𝐴 ∈ {𝑥 ∈ 𝐵 ∣ 𝜑} ↔ (𝐴 ∈ 𝐵 ∧ 𝜓))
5	2, 4	bitri 182	1 ⊢ (𝐴 ∈ 𝐶 ↔ (𝐴 ∈ 𝐵 ∧ 𝜓))

Colors of variables: wff set class

Syntax hints: → wi 4 ∧ wa 102 ↔ wb 103 = wceq 1284 ∈ wcel 1433 {crab 2352

This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-io 662 ax-5 1376 ax-7 1377 ax-gen 1378 ax-ie1 1422 ax-ie2 1423 ax-8 1435 ax-10 1436 ax-11 1437 ax-i12 1438 ax-bndl 1439 ax-4 1440 ax-17 1459 ax-i9 1463 ax-ial 1467 ax-i5r 1468 ax-ext 2063

This theorem depends on definitions: df-bi 115 df-tru 1287 df-nf 1390 df-sb 1686 df-clab 2068 df-cleq 2074 df-clel 2077 df-nfc 2208 df-rab 2357 df-v 2603