Theorem abrexco 5806

Description: Composition of two image maps 𝐶(𝑦) and 𝐵(𝑤). (Contributed by NM, 27-May-2013.)

Hypotheses

Ref	Expression
abrexco.1	⊢ 𝐵 ∈ V
abrexco.2	⊢ (𝑦 = 𝐵 → 𝐶 = 𝐷)

Assertion

Ref	Expression
abrexco	⊢ {𝑥 ∣ ∃𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵}𝑥 = 𝐶} = {𝑥 ∣ ∃𝑤 ∈ 𝐴 𝑥 = 𝐷}

Distinct variable groups:   𝑦,𝐴,𝑧   𝑦,𝐵,𝑧   𝑤,𝐶   𝑦,𝐷   𝑥,𝑤,𝑦   𝑧,𝑤

Allowed substitution hints:   𝐴(𝑥,𝑤)   𝐵(𝑥,𝑤)   𝐶(𝑥,𝑦,𝑧)   𝐷(𝑥,𝑧,𝑤)

Proof of Theorem abrexco

Step	Hyp	Ref	Expression
1		df-rex 2481	. . . . 5 ⊢ (∃𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵}𝑥 = 𝐶 ↔ ∃𝑦(𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵} ∧ 𝑥 = 𝐶))
2		vex 2766	. . . . . . . . 9 ⊢ 𝑦 ∈ V
3		eqeq1 2203	. . . . . . . . . 10 ⊢ (𝑧 = 𝑦 → (𝑧 = 𝐵 ↔ 𝑦 = 𝐵))
4	3	rexbidv 2498	. . . . . . . . 9 ⊢ (𝑧 = 𝑦 → (∃𝑤 ∈ 𝐴 𝑧 = 𝐵 ↔ ∃𝑤 ∈ 𝐴 𝑦 = 𝐵))
5	2, 4	elab 2908	. . . . . . . 8 ⊢ (𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵} ↔ ∃𝑤 ∈ 𝐴 𝑦 = 𝐵)
6	5	anbi1i 458	. . . . . . 7 ⊢ ((𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵} ∧ 𝑥 = 𝐶) ↔ (∃𝑤 ∈ 𝐴 𝑦 = 𝐵 ∧ 𝑥 = 𝐶))
7		r19.41v 2653	. . . . . . 7 ⊢ (∃𝑤 ∈ 𝐴 (𝑦 = 𝐵 ∧ 𝑥 = 𝐶) ↔ (∃𝑤 ∈ 𝐴 𝑦 = 𝐵 ∧ 𝑥 = 𝐶))
8	6, 7	bitr4i 187	. . . . . 6 ⊢ ((𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵} ∧ 𝑥 = 𝐶) ↔ ∃𝑤 ∈ 𝐴 (𝑦 = 𝐵 ∧ 𝑥 = 𝐶))
9	8	exbii 1619	. . . . 5 ⊢ (∃𝑦(𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵} ∧ 𝑥 = 𝐶) ↔ ∃𝑦∃𝑤 ∈ 𝐴 (𝑦 = 𝐵 ∧ 𝑥 = 𝐶))
10	1, 9	bitri 184	. . . 4 ⊢ (∃𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵}𝑥 = 𝐶 ↔ ∃𝑦∃𝑤 ∈ 𝐴 (𝑦 = 𝐵 ∧ 𝑥 = 𝐶))
11		rexcom4 2786	. . . 4 ⊢ (∃𝑤 ∈ 𝐴 ∃𝑦(𝑦 = 𝐵 ∧ 𝑥 = 𝐶) ↔ ∃𝑦∃𝑤 ∈ 𝐴 (𝑦 = 𝐵 ∧ 𝑥 = 𝐶))
12	10, 11	bitr4i 187	. . 3 ⊢ (∃𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵}𝑥 = 𝐶 ↔ ∃𝑤 ∈ 𝐴 ∃𝑦(𝑦 = 𝐵 ∧ 𝑥 = 𝐶))
13		abrexco.1	. . . . 5 ⊢ 𝐵 ∈ V
14		abrexco.2	. . . . . 6 ⊢ (𝑦 = 𝐵 → 𝐶 = 𝐷)
15	14	eqeq2d 2208	. . . . 5 ⊢ (𝑦 = 𝐵 → (𝑥 = 𝐶 ↔ 𝑥 = 𝐷))
16	13, 15	ceqsexv 2802	. . . 4 ⊢ (∃𝑦(𝑦 = 𝐵 ∧ 𝑥 = 𝐶) ↔ 𝑥 = 𝐷)
17	16	rexbii 2504	. . 3 ⊢ (∃𝑤 ∈ 𝐴 ∃𝑦(𝑦 = 𝐵 ∧ 𝑥 = 𝐶) ↔ ∃𝑤 ∈ 𝐴 𝑥 = 𝐷)
18	12, 17	bitri 184	. 2 ⊢ (∃𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵}𝑥 = 𝐶 ↔ ∃𝑤 ∈ 𝐴 𝑥 = 𝐷)
19	18	abbii 2312	1 ⊢ {𝑥 ∣ ∃𝑦 ∈ {𝑧 ∣ ∃𝑤 ∈ 𝐴 𝑧 = 𝐵}𝑥 = 𝐶} = {𝑥 ∣ ∃𝑤 ∈ 𝐴 𝑥 = 𝐷}

Syntax hints:   → wi 4   ∧ wa 104   = wceq 1364  ∃wex 1506   ∈ wcel 2167  {cab 2182  ∃wrex 2476  Vcvv 2763

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-rex 2481  df-v 2765

This theorem is referenced by:  restco  14410