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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 3435 | . . . . . . 7 ⊢ 𝑥 ∈ V | |
| 2 | vex 3435 | . . . . . . 7 ⊢ 𝑦 ∈ V | |
| 3 | 1, 2 | opnzi 5414 | . . . . . 6 ⊢ 〈𝑥, 𝑦〉 ≠ ∅ |
| 4 | 3 | nesymi 2991 | . . . . 5 ⊢ ¬ ∅ = 〈𝑥, 𝑦〉 |
| 5 | 4 | intnanr 488 | . . . 4 ⊢ ¬ (∅ = 〈𝑥, 𝑦〉 ∧ 𝜑) |
| 6 | 5 | nex 1807 | . . 3 ⊢ ¬ ∃𝑦(∅ = 〈𝑥, 𝑦〉 ∧ 𝜑) |
| 7 | 6 | nex 1807 | . 2 ⊢ ¬ ∃𝑥∃𝑦(∅ = 〈𝑥, 𝑦〉 ∧ 𝜑) |
| 8 | elopab 5469 | . 2 ⊢ (∅ ∈ {〈𝑥, 𝑦〉 ∣ 𝜑} ↔ ∃𝑥∃𝑦(∅ = 〈𝑥, 𝑦〉 ∧ 𝜑)) | |
| 9 | 7, 8 | mtbir 324 | 1 ⊢ ¬ ∅ ∈ {〈𝑥, 𝑦〉 ∣ 𝜑} |
| Colors of variables: wff setvar class |
| Syntax hints: ¬ wn 3 ∧ wa 396 = wceq 1547 ∃wex 1786 ∈ wcel 2119 ∅c0 4261 〈cop 4561 {copab 5134 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1917 ax-6 1974 ax-7 2015 ax-8 2121 ax-9 2129 ax-ext 2711 ax-sep 5218 ax-pr 5362 |
| This theorem depends on definitions: df-bi 208 df-an 397 df-or 854 df-3an 1094 df-tru 1550 df-fal 1560 df-ex 1787 df-sb 2074 df-clab 2718 df-cleq 2731 df-clel 2814 df-ne 2935 df-rab 3392 df-v 3433 df-dif 3886 df-un 3888 df-in 3890 df-ss 3900 df-nul 4262 df-if 4455 df-sn 4556 df-pr 4558 df-op 4562 df-opab 5135 |
| This theorem is referenced by: brabv 5508 epelg 5519 satf0n0 35606 bj-0nelmpt 37474 |
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