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Mirrors > Home > MPE Home > Th. List > class2set | Structured version Visualization version GIF version |
Description: The class of elements of 𝐴 "such that 𝐴 is a set" is a set. That class is equal to 𝐴 when 𝐴 is a set (see class2seteq 3697) and to the empty set when 𝐴 is a proper class. (Contributed by NM, 16-Oct-2003.) |
Ref | Expression |
---|---|
class2set | ⊢ {𝑥 ∈ 𝐴 ∣ 𝐴 ∈ V} ∈ V |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | rabexg 5327 | . 2 ⊢ (𝐴 ∈ V → {𝑥 ∈ 𝐴 ∣ 𝐴 ∈ V} ∈ V) | |
2 | simpl 482 | . . . . 5 ⊢ ((¬ 𝐴 ∈ V ∧ 𝑥 ∈ 𝐴) → ¬ 𝐴 ∈ V) | |
3 | 2 | nrexdv 3144 | . . . 4 ⊢ (¬ 𝐴 ∈ V → ¬ ∃𝑥 ∈ 𝐴 𝐴 ∈ V) |
4 | rabn0 4381 | . . . . 5 ⊢ ({𝑥 ∈ 𝐴 ∣ 𝐴 ∈ V} ≠ ∅ ↔ ∃𝑥 ∈ 𝐴 𝐴 ∈ V) | |
5 | 4 | necon1bbii 2985 | . . . 4 ⊢ (¬ ∃𝑥 ∈ 𝐴 𝐴 ∈ V ↔ {𝑥 ∈ 𝐴 ∣ 𝐴 ∈ V} = ∅) |
6 | 3, 5 | sylib 217 | . . 3 ⊢ (¬ 𝐴 ∈ V → {𝑥 ∈ 𝐴 ∣ 𝐴 ∈ V} = ∅) |
7 | 0ex 5301 | . . 3 ⊢ ∅ ∈ V | |
8 | 6, 7 | eqeltrdi 2836 | . 2 ⊢ (¬ 𝐴 ∈ V → {𝑥 ∈ 𝐴 ∣ 𝐴 ∈ V} ∈ V) |
9 | 1, 8 | pm2.61i 182 | 1 ⊢ {𝑥 ∈ 𝐴 ∣ 𝐴 ∈ V} ∈ V |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 = wceq 1534 ∈ wcel 2099 ∃wrex 3065 {crab 3427 Vcvv 3469 ∅c0 4318 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1906 ax-6 1964 ax-7 2004 ax-8 2101 ax-9 2109 ax-10 2130 ax-11 2147 ax-12 2164 ax-ext 2698 ax-sep 5293 ax-nul 5300 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 847 df-tru 1537 df-fal 1547 df-ex 1775 df-nf 1779 df-sb 2061 df-clab 2705 df-cleq 2719 df-clel 2805 df-ne 2936 df-ral 3057 df-rex 3066 df-rab 3428 df-v 3471 df-dif 3947 df-in 3951 df-ss 3961 df-nul 4319 |
This theorem is referenced by: (None) |
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