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Mirrors > Home > ILE Home > Th. List > axpweq | GIF version |
Description: Two equivalent ways to express the Power Set Axiom. Note that ax-pow 3948 is not used by the proof. (Contributed by NM, 22-Jun-2009.) |
Ref | Expression |
---|---|
axpweq.1 | ⊢ 𝐴 ∈ V |
Ref | Expression |
---|---|
axpweq | ⊢ (𝒫 𝐴 ∈ V ↔ ∃𝑥∀𝑦(∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴) → 𝑦 ∈ 𝑥)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pwidg 3395 | . . . 4 ⊢ (𝒫 𝐴 ∈ V → 𝒫 𝐴 ∈ 𝒫 𝒫 𝐴) | |
2 | pweq 3385 | . . . . . 6 ⊢ (𝑥 = 𝒫 𝐴 → 𝒫 𝑥 = 𝒫 𝒫 𝐴) | |
3 | 2 | eleq2d 2148 | . . . . 5 ⊢ (𝑥 = 𝒫 𝐴 → (𝒫 𝐴 ∈ 𝒫 𝑥 ↔ 𝒫 𝐴 ∈ 𝒫 𝒫 𝐴)) |
4 | 3 | spcegv 2686 | . . . 4 ⊢ (𝒫 𝐴 ∈ V → (𝒫 𝐴 ∈ 𝒫 𝒫 𝐴 → ∃𝑥𝒫 𝐴 ∈ 𝒫 𝑥)) |
5 | 1, 4 | mpd 13 | . . 3 ⊢ (𝒫 𝐴 ∈ V → ∃𝑥𝒫 𝐴 ∈ 𝒫 𝑥) |
6 | elex 2610 | . . . 4 ⊢ (𝒫 𝐴 ∈ 𝒫 𝑥 → 𝒫 𝐴 ∈ V) | |
7 | 6 | exlimiv 1529 | . . 3 ⊢ (∃𝑥𝒫 𝐴 ∈ 𝒫 𝑥 → 𝒫 𝐴 ∈ V) |
8 | 5, 7 | impbii 124 | . 2 ⊢ (𝒫 𝐴 ∈ V ↔ ∃𝑥𝒫 𝐴 ∈ 𝒫 𝑥) |
9 | vex 2604 | . . . . 5 ⊢ 𝑥 ∈ V | |
10 | 9 | elpw2 3932 | . . . 4 ⊢ (𝒫 𝐴 ∈ 𝒫 𝑥 ↔ 𝒫 𝐴 ⊆ 𝑥) |
11 | pwss 3397 | . . . . 5 ⊢ (𝒫 𝐴 ⊆ 𝑥 ↔ ∀𝑦(𝑦 ⊆ 𝐴 → 𝑦 ∈ 𝑥)) | |
12 | dfss2 2988 | . . . . . . 7 ⊢ (𝑦 ⊆ 𝐴 ↔ ∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴)) | |
13 | 12 | imbi1i 236 | . . . . . 6 ⊢ ((𝑦 ⊆ 𝐴 → 𝑦 ∈ 𝑥) ↔ (∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴) → 𝑦 ∈ 𝑥)) |
14 | 13 | albii 1399 | . . . . 5 ⊢ (∀𝑦(𝑦 ⊆ 𝐴 → 𝑦 ∈ 𝑥) ↔ ∀𝑦(∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴) → 𝑦 ∈ 𝑥)) |
15 | 11, 14 | bitri 182 | . . . 4 ⊢ (𝒫 𝐴 ⊆ 𝑥 ↔ ∀𝑦(∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴) → 𝑦 ∈ 𝑥)) |
16 | 10, 15 | bitri 182 | . . 3 ⊢ (𝒫 𝐴 ∈ 𝒫 𝑥 ↔ ∀𝑦(∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴) → 𝑦 ∈ 𝑥)) |
17 | 16 | exbii 1536 | . 2 ⊢ (∃𝑥𝒫 𝐴 ∈ 𝒫 𝑥 ↔ ∃𝑥∀𝑦(∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴) → 𝑦 ∈ 𝑥)) |
18 | 8, 17 | bitri 182 | 1 ⊢ (𝒫 𝐴 ∈ V ↔ ∃𝑥∀𝑦(∀𝑧(𝑧 ∈ 𝑦 → 𝑧 ∈ 𝐴) → 𝑦 ∈ 𝑥)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ↔ wb 103 ∀wal 1282 = wceq 1284 ∃wex 1421 ∈ wcel 1433 Vcvv 2601 ⊆ wss 2973 𝒫 cpw 3382 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-io 662 ax-5 1376 ax-7 1377 ax-gen 1378 ax-ie1 1422 ax-ie2 1423 ax-8 1435 ax-10 1436 ax-11 1437 ax-i12 1438 ax-bndl 1439 ax-4 1440 ax-17 1459 ax-i9 1463 ax-ial 1467 ax-i5r 1468 ax-ext 2063 ax-sep 3896 |
This theorem depends on definitions: df-bi 115 df-tru 1287 df-nf 1390 df-sb 1686 df-clab 2068 df-cleq 2074 df-clel 2077 df-nfc 2208 df-v 2603 df-in 2979 df-ss 2986 df-pw 3384 |
This theorem is referenced by: (None) |
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