elrab2 - Intuitionistic Logic Explorer

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Theorem elrab2 2700

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 2104	. 2 ⊢ (𝐴 ∈ 𝐶 ↔ 𝐴 ∈ {𝑥 ∈ 𝐵 ∣ 𝜑})
3		elrab2.1	. . 3 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓))
4	3	elrab 2698	. 2 ⊢ (𝐴 ∈ {𝑥 ∈ 𝐵 ∣ 𝜑} ↔ (𝐴 ∈ 𝐵 ∧ 𝜓))
5	2, 4	bitri 173	1 ⊢ (𝐴 ∈ 𝐶 ↔ (𝐴 ∈ 𝐵 ∧ 𝜓))

Colors of variables: wff set class

Syntax hints: → wi 4 ∧ wa 97 ↔ wb 98 = wceq 1243 ∈ wcel 1393 {crab 2310

This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-io 630 ax-5 1336 ax-7 1337 ax-gen 1338 ax-ie1 1382 ax-ie2 1383 ax-8 1395 ax-10 1396 ax-11 1397 ax-i12 1398 ax-bndl 1399 ax-4 1400 ax-17 1419 ax-i9 1423 ax-ial 1427 ax-i5r 1428 ax-ext 2022

This theorem depends on definitions: df-bi 110 df-tru 1246 df-nf 1350 df-sb 1646 df-clab 2027 df-cleq 2033 df-clel 2036 df-nfc 2167 df-rab 2315 df-v 2559