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Theorem imaco 4826
 Description: Image of the composition of two classes. (Contributed by Jason Orendorff, 12-Dec-2006.)
Assertion
Ref Expression
imaco ((𝐴𝐵) “ 𝐶) = (𝐴 “ (𝐵𝐶))

Proof of Theorem imaco
Dummy variables 𝑥 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 df-rex 2312 . . 3 (∃𝑦 ∈ (𝐵𝐶)𝑦𝐴𝑥 ↔ ∃𝑦(𝑦 ∈ (𝐵𝐶) ∧ 𝑦𝐴𝑥))
2 vex 2560 . . . 4 𝑥 ∈ V
32elima 4673 . . 3 (𝑥 ∈ (𝐴 “ (𝐵𝐶)) ↔ ∃𝑦 ∈ (𝐵𝐶)𝑦𝐴𝑥)
4 rexcom4 2577 . . . . 5 (∃𝑧𝐶𝑦(𝑧𝐵𝑦𝑦𝐴𝑥) ↔ ∃𝑦𝑧𝐶 (𝑧𝐵𝑦𝑦𝐴𝑥))
5 r19.41v 2466 . . . . . 6 (∃𝑧𝐶 (𝑧𝐵𝑦𝑦𝐴𝑥) ↔ (∃𝑧𝐶 𝑧𝐵𝑦𝑦𝐴𝑥))
65exbii 1496 . . . . 5 (∃𝑦𝑧𝐶 (𝑧𝐵𝑦𝑦𝐴𝑥) ↔ ∃𝑦(∃𝑧𝐶 𝑧𝐵𝑦𝑦𝐴𝑥))
74, 6bitri 173 . . . 4 (∃𝑧𝐶𝑦(𝑧𝐵𝑦𝑦𝐴𝑥) ↔ ∃𝑦(∃𝑧𝐶 𝑧𝐵𝑦𝑦𝐴𝑥))
82elima 4673 . . . . 5 (𝑥 ∈ ((𝐴𝐵) “ 𝐶) ↔ ∃𝑧𝐶 𝑧(𝐴𝐵)𝑥)
9 vex 2560 . . . . . . 7 𝑧 ∈ V
109, 2brco 4506 . . . . . 6 (𝑧(𝐴𝐵)𝑥 ↔ ∃𝑦(𝑧𝐵𝑦𝑦𝐴𝑥))
1110rexbii 2331 . . . . 5 (∃𝑧𝐶 𝑧(𝐴𝐵)𝑥 ↔ ∃𝑧𝐶𝑦(𝑧𝐵𝑦𝑦𝐴𝑥))
128, 11bitri 173 . . . 4 (𝑥 ∈ ((𝐴𝐵) “ 𝐶) ↔ ∃𝑧𝐶𝑦(𝑧𝐵𝑦𝑦𝐴𝑥))
13 vex 2560 . . . . . . 7 𝑦 ∈ V
1413elima 4673 . . . . . 6 (𝑦 ∈ (𝐵𝐶) ↔ ∃𝑧𝐶 𝑧𝐵𝑦)
1514anbi1i 431 . . . . 5 ((𝑦 ∈ (𝐵𝐶) ∧ 𝑦𝐴𝑥) ↔ (∃𝑧𝐶 𝑧𝐵𝑦𝑦𝐴𝑥))
1615exbii 1496 . . . 4 (∃𝑦(𝑦 ∈ (𝐵𝐶) ∧ 𝑦𝐴𝑥) ↔ ∃𝑦(∃𝑧𝐶 𝑧𝐵𝑦𝑦𝐴𝑥))
177, 12, 163bitr4i 201 . . 3 (𝑥 ∈ ((𝐴𝐵) “ 𝐶) ↔ ∃𝑦(𝑦 ∈ (𝐵𝐶) ∧ 𝑦𝐴𝑥))
181, 3, 173bitr4ri 202 . 2 (𝑥 ∈ ((𝐴𝐵) “ 𝐶) ↔ 𝑥 ∈ (𝐴 “ (𝐵𝐶)))
1918eqriv 2037 1 ((𝐴𝐵) “ 𝐶) = (𝐴 “ (𝐵𝐶))
 Colors of variables: wff set class Syntax hints:   ∧ wa 97   = wceq 1243  ∃wex 1381   ∈ wcel 1393  ∃wrex 2307   class class class wbr 3764   “ cima 4348   ∘ ccom 4349 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-14 1405  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022  ax-sep 3875  ax-pow 3927  ax-pr 3944 This theorem depends on definitions:  df-bi 110  df-3an 887  df-tru 1246  df-nf 1350  df-sb 1646  df-eu 1903  df-mo 1904  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ral 2311  df-rex 2312  df-v 2559  df-un 2922  df-in 2924  df-ss 2931  df-pw 3361  df-sn 3381  df-pr 3382  df-op 3384  df-br 3765  df-opab 3819  df-xp 4351  df-cnv 4353  df-co 4354  df-dm 4355  df-rn 4356  df-res 4357  df-ima 4358 This theorem is referenced by:  fvco2  5242
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