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| Mirrors > Home > ILE Home > Th. List > vpwex | GIF version | ||
| Description: Power set axiom: the powerclass of a set is a set. Axiom 4 of [TakeutiZaring] p. 17. (Contributed by NM, 30-Oct-2003.) (Proof shortened by Andrew Salmon, 25-Jul-2011.) Revised to prove pwexg 4213 from vpwex 4212. (Revised by BJ, 10-Aug-2022.) | 
| Ref | Expression | 
|---|---|
| vpwex | ⊢ 𝒫 𝑥 ∈ V | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | df-pw 3607 | . 2 ⊢ 𝒫 𝑥 = {𝑦 ∣ 𝑦 ⊆ 𝑥} | |
| 2 | axpow2 4209 | . . . . 5 ⊢ ∃𝑧∀𝑦(𝑦 ⊆ 𝑥 → 𝑦 ∈ 𝑧) | |
| 3 | 2 | bm1.3ii 4154 | . . . 4 ⊢ ∃𝑧∀𝑦(𝑦 ∈ 𝑧 ↔ 𝑦 ⊆ 𝑥) | 
| 4 | abeq2 2305 | . . . . 5 ⊢ (𝑧 = {𝑦 ∣ 𝑦 ⊆ 𝑥} ↔ ∀𝑦(𝑦 ∈ 𝑧 ↔ 𝑦 ⊆ 𝑥)) | |
| 5 | 4 | exbii 1619 | . . . 4 ⊢ (∃𝑧 𝑧 = {𝑦 ∣ 𝑦 ⊆ 𝑥} ↔ ∃𝑧∀𝑦(𝑦 ∈ 𝑧 ↔ 𝑦 ⊆ 𝑥)) | 
| 6 | 3, 5 | mpbir 146 | . . 3 ⊢ ∃𝑧 𝑧 = {𝑦 ∣ 𝑦 ⊆ 𝑥} | 
| 7 | 6 | issetri 2772 | . 2 ⊢ {𝑦 ∣ 𝑦 ⊆ 𝑥} ∈ V | 
| 8 | 1, 7 | eqeltri 2269 | 1 ⊢ 𝒫 𝑥 ∈ V | 
| Colors of variables: wff set class | 
| Syntax hints: ↔ wb 105 ∀wal 1362 = wceq 1364 ∃wex 1506 ∈ wcel 2167 {cab 2182 Vcvv 2763 ⊆ wss 3157 𝒫 cpw 3605 | 
| 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-5 1461 ax-7 1462 ax-gen 1463 ax-ie1 1507 ax-ie2 1508 ax-8 1518 ax-11 1520 ax-4 1524 ax-17 1540 ax-i9 1544 ax-ial 1548 ax-i5r 1549 ax-14 2170 ax-ext 2178 ax-sep 4151 ax-pow 4207 | 
| This theorem depends on definitions: df-bi 117 df-nf 1475 df-sb 1777 df-clab 2183 df-cleq 2189 df-clel 2192 df-v 2765 df-in 3163 df-ss 3170 df-pw 3607 | 
| This theorem is referenced by: pwexg 4213 pwnex 4484 exmidpw2en 6973 metuex 14111 istopon 14249 dmtopon 14259 tgdom 14308 | 
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