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Mirrors > Home > MPE Home > Th. List > bm1.1 | Structured version Visualization version GIF version |
Description: Any set defined by a property is the only set defined by that property. Theorem 1.1 of [BellMachover] p. 462. (Contributed by NM, 30-Jun-1994.) (Proof shortened by Wolf Lammen, 13-Nov-2019.) |
Ref | Expression |
---|---|
bm1.1.1 | ⊢ Ⅎ𝑥𝜑 |
Ref | Expression |
---|---|
bm1.1 | ⊢ (∃𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) → ∃!𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | biantr 968 | . . . . 5 ⊢ (((𝑦 ∈ 𝑥 ↔ 𝜑) ∧ (𝑦 ∈ 𝑧 ↔ 𝜑)) → (𝑦 ∈ 𝑥 ↔ 𝑦 ∈ 𝑧)) | |
2 | 1 | alanimi 1734 | . . . 4 ⊢ ((∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ∧ ∀𝑦(𝑦 ∈ 𝑧 ↔ 𝜑)) → ∀𝑦(𝑦 ∈ 𝑥 ↔ 𝑦 ∈ 𝑧)) |
3 | ax-ext 2590 | . . . 4 ⊢ (∀𝑦(𝑦 ∈ 𝑥 ↔ 𝑦 ∈ 𝑧) → 𝑥 = 𝑧) | |
4 | 2, 3 | syl 17 | . . 3 ⊢ ((∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ∧ ∀𝑦(𝑦 ∈ 𝑧 ↔ 𝜑)) → 𝑥 = 𝑧) |
5 | 4 | gen2 1714 | . 2 ⊢ ∀𝑥∀𝑧((∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ∧ ∀𝑦(𝑦 ∈ 𝑧 ↔ 𝜑)) → 𝑥 = 𝑧) |
6 | nfv 1830 | . . . . . 6 ⊢ Ⅎ𝑥 𝑦 ∈ 𝑧 | |
7 | bm1.1.1 | . . . . . 6 ⊢ Ⅎ𝑥𝜑 | |
8 | 6, 7 | nfbi 1821 | . . . . 5 ⊢ Ⅎ𝑥(𝑦 ∈ 𝑧 ↔ 𝜑) |
9 | 8 | nfal 2139 | . . . 4 ⊢ Ⅎ𝑥∀𝑦(𝑦 ∈ 𝑧 ↔ 𝜑) |
10 | elequ2 1991 | . . . . . 6 ⊢ (𝑥 = 𝑧 → (𝑦 ∈ 𝑥 ↔ 𝑦 ∈ 𝑧)) | |
11 | 10 | bibi1d 332 | . . . . 5 ⊢ (𝑥 = 𝑧 → ((𝑦 ∈ 𝑥 ↔ 𝜑) ↔ (𝑦 ∈ 𝑧 ↔ 𝜑))) |
12 | 11 | albidv 1836 | . . . 4 ⊢ (𝑥 = 𝑧 → (∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ↔ ∀𝑦(𝑦 ∈ 𝑧 ↔ 𝜑))) |
13 | 9, 12 | mo4f 2504 | . . 3 ⊢ (∃*𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ↔ ∀𝑥∀𝑧((∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ∧ ∀𝑦(𝑦 ∈ 𝑧 ↔ 𝜑)) → 𝑥 = 𝑧)) |
14 | df-mo 2463 | . . 3 ⊢ (∃*𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ↔ (∃𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) → ∃!𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑))) | |
15 | 13, 14 | bitr3i 265 | . 2 ⊢ (∀𝑥∀𝑧((∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) ∧ ∀𝑦(𝑦 ∈ 𝑧 ↔ 𝜑)) → 𝑥 = 𝑧) ↔ (∃𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) → ∃!𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑))) |
16 | 5, 15 | mpbi 219 | 1 ⊢ (∃𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑) → ∃!𝑥∀𝑦(𝑦 ∈ 𝑥 ↔ 𝜑)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 195 ∧ wa 383 ∀wal 1473 ∃wex 1695 Ⅎwnf 1699 ∃!weu 2458 ∃*wmo 2459 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1713 ax-4 1728 ax-5 1827 ax-6 1875 ax-7 1922 ax-9 1986 ax-10 2006 ax-11 2021 ax-12 2034 ax-13 2234 ax-ext 2590 |
This theorem depends on definitions: df-bi 196 df-or 384 df-an 385 df-tru 1478 df-ex 1696 df-nf 1701 df-sb 1868 df-eu 2462 df-mo 2463 |
This theorem is referenced by: zfnuleu 4714 |
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