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| Mirrors > Home > MPE Home > Th. List > 0nelopab | Structured version Visualization version GIF version | ||
| Description: The empty set is never an element in an ordered-pair class abstraction. (Contributed by Alexander van der Vekens, 5-Nov-2017.) Reduce axiom usage and shorten proof. (Revised by GG, 3-Oct-2024.) |
| Ref | Expression |
|---|---|
| 0nelopab | ⊢ ¬ ∅ ∈ {〈𝑥, 𝑦〉 ∣ 𝜑} |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | vex 3454 | . . . . . . 7 ⊢ 𝑥 ∈ V | |
| 2 | vex 3454 | . . . . . . 7 ⊢ 𝑦 ∈ V | |
| 3 | 1, 2 | opnzi 5437 | . . . . . 6 ⊢ 〈𝑥, 𝑦〉 ≠ ∅ |
| 4 | 3 | nesymi 2983 | . . . . 5 ⊢ ¬ ∅ = 〈𝑥, 𝑦〉 |
| 5 | 4 | intnanr 487 | . . . 4 ⊢ ¬ (∅ = 〈𝑥, 𝑦〉 ∧ 𝜑) |
| 6 | 5 | nex 1800 | . . 3 ⊢ ¬ ∃𝑦(∅ = 〈𝑥, 𝑦〉 ∧ 𝜑) |
| 7 | 6 | nex 1800 | . 2 ⊢ ¬ ∃𝑥∃𝑦(∅ = 〈𝑥, 𝑦〉 ∧ 𝜑) |
| 8 | elopab 5490 | . 2 ⊢ (∅ ∈ {〈𝑥, 𝑦〉 ∣ 𝜑} ↔ ∃𝑥∃𝑦(∅ = 〈𝑥, 𝑦〉 ∧ 𝜑)) | |
| 9 | 7, 8 | mtbir 323 | 1 ⊢ ¬ ∅ ∈ {〈𝑥, 𝑦〉 ∣ 𝜑} |
| Colors of variables: wff setvar class |
| Syntax hints: ¬ wn 3 ∧ wa 395 = wceq 1540 ∃wex 1779 ∈ wcel 2109 ∅c0 4299 〈cop 4598 {copab 5172 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1967 ax-7 2008 ax-8 2111 ax-9 2119 ax-ext 2702 ax-sep 5254 ax-nul 5264 ax-pr 5390 |
| This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3an 1088 df-tru 1543 df-fal 1553 df-ex 1780 df-sb 2066 df-clab 2709 df-cleq 2722 df-clel 2804 df-ne 2927 df-v 3452 df-dif 3920 df-un 3922 df-ss 3934 df-nul 4300 df-if 4492 df-sn 4593 df-pr 4595 df-op 4599 df-opab 5173 |
| This theorem is referenced by: brabv 5531 epelg 5542 satf0n0 35372 bj-0nelmpt 37111 |
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