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Mirrors > Home > ILE Home > Th. List > djuexb | GIF version |
Description: The disjoint union of two classes is a set iff both classes are sets. (Contributed by Jim Kingdon, 6-Sep-2023.) |
Ref | Expression |
---|---|
djuexb | ⊢ ((𝐴 ∈ V ∧ 𝐵 ∈ V) ↔ (𝐴 ⊔ 𝐵) ∈ V) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | djuex 7088 | . 2 ⊢ ((𝐴 ∈ V ∧ 𝐵 ∈ V) → (𝐴 ⊔ 𝐵) ∈ V) | |
2 | df-dju 7083 | . . . . 5 ⊢ (𝐴 ⊔ 𝐵) = (({∅} × 𝐴) ∪ ({1o} × 𝐵)) | |
3 | 2 | eleq1i 2255 | . . . 4 ⊢ ((𝐴 ⊔ 𝐵) ∈ V ↔ (({∅} × 𝐴) ∪ ({1o} × 𝐵)) ∈ V) |
4 | unexb 4467 | . . . 4 ⊢ ((({∅} × 𝐴) ∈ V ∧ ({1o} × 𝐵) ∈ V) ↔ (({∅} × 𝐴) ∪ ({1o} × 𝐵)) ∈ V) | |
5 | 3, 4 | bitr4i 187 | . . 3 ⊢ ((𝐴 ⊔ 𝐵) ∈ V ↔ (({∅} × 𝐴) ∈ V ∧ ({1o} × 𝐵) ∈ V)) |
6 | 0ex 4152 | . . . . . . 7 ⊢ ∅ ∈ V | |
7 | 6 | snm 3734 | . . . . . 6 ⊢ ∃𝑥 𝑥 ∈ {∅} |
8 | rnxpm 5083 | . . . . . 6 ⊢ (∃𝑥 𝑥 ∈ {∅} → ran ({∅} × 𝐴) = 𝐴) | |
9 | 7, 8 | ax-mp 5 | . . . . 5 ⊢ ran ({∅} × 𝐴) = 𝐴 |
10 | rnexg 4917 | . . . . 5 ⊢ (({∅} × 𝐴) ∈ V → ran ({∅} × 𝐴) ∈ V) | |
11 | 9, 10 | eqeltrrid 2277 | . . . 4 ⊢ (({∅} × 𝐴) ∈ V → 𝐴 ∈ V) |
12 | 1oex 6464 | . . . . . . 7 ⊢ 1o ∈ V | |
13 | 12 | snm 3734 | . . . . . 6 ⊢ ∃𝑥 𝑥 ∈ {1o} |
14 | rnxpm 5083 | . . . . . 6 ⊢ (∃𝑥 𝑥 ∈ {1o} → ran ({1o} × 𝐵) = 𝐵) | |
15 | 13, 14 | ax-mp 5 | . . . . 5 ⊢ ran ({1o} × 𝐵) = 𝐵 |
16 | rnexg 4917 | . . . . 5 ⊢ (({1o} × 𝐵) ∈ V → ran ({1o} × 𝐵) ∈ V) | |
17 | 15, 16 | eqeltrrid 2277 | . . . 4 ⊢ (({1o} × 𝐵) ∈ V → 𝐵 ∈ V) |
18 | 11, 17 | anim12i 338 | . . 3 ⊢ ((({∅} × 𝐴) ∈ V ∧ ({1o} × 𝐵) ∈ V) → (𝐴 ∈ V ∧ 𝐵 ∈ V)) |
19 | 5, 18 | sylbi 121 | . 2 ⊢ ((𝐴 ⊔ 𝐵) ∈ V → (𝐴 ∈ V ∧ 𝐵 ∈ V)) |
20 | 1, 19 | impbii 126 | 1 ⊢ ((𝐴 ∈ V ∧ 𝐵 ∈ V) ↔ (𝐴 ⊔ 𝐵) ∈ V) |
Colors of variables: wff set class |
Syntax hints: ∧ wa 104 ↔ wb 105 = wceq 1364 ∃wex 1503 ∈ wcel 2160 Vcvv 2756 ∪ cun 3147 ∅c0 3442 {csn 3614 × cxp 4649 ran crn 4652 1oc1o 6449 ⊔ cdju 7082 |
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-in1 615 ax-in2 616 ax-io 710 ax-5 1458 ax-7 1459 ax-gen 1460 ax-ie1 1504 ax-ie2 1505 ax-8 1515 ax-10 1516 ax-11 1517 ax-i12 1518 ax-bndl 1520 ax-4 1521 ax-17 1537 ax-i9 1541 ax-ial 1545 ax-i5r 1546 ax-13 2162 ax-14 2163 ax-ext 2171 ax-sep 4143 ax-nul 4151 ax-pow 4199 ax-pr 4234 ax-un 4458 |
This theorem depends on definitions: df-bi 117 df-3an 982 df-tru 1367 df-nf 1472 df-sb 1774 df-eu 2041 df-mo 2042 df-clab 2176 df-cleq 2182 df-clel 2185 df-nfc 2321 df-ral 2473 df-rex 2474 df-v 2758 df-dif 3151 df-un 3153 df-in 3155 df-ss 3162 df-nul 3443 df-pw 3599 df-sn 3620 df-pr 3621 df-op 3623 df-uni 3832 df-br 4026 df-opab 4087 df-tr 4124 df-iord 4391 df-on 4393 df-suc 4396 df-xp 4657 df-rel 4658 df-cnv 4659 df-dm 4661 df-rn 4662 df-1o 6456 df-dju 7083 |
This theorem is referenced by: ctfoex 7163 |
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