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Mirrors > Home > MPE Home > Th. List > Mathboxes > bj-rest10 | Structured version Visualization version GIF version |
Description: An elementwise intersection on a nonempty family by the empty set is the singleton on the empty set. TODO: this generalizes rest0 21705 and could replace it. (Contributed by BJ, 27-Apr-2021.) |
Ref | Expression |
---|---|
bj-rest10 | ⊢ (𝑋 ∈ 𝑉 → (𝑋 ≠ ∅ → (𝑋 ↾t ∅) = {∅})) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ex 5202 | . . . . . 6 ⊢ ∅ ∈ V | |
2 | elrest 16689 | . . . . . 6 ⊢ ((𝑋 ∈ 𝑉 ∧ ∅ ∈ V) → (𝑥 ∈ (𝑋 ↾t ∅) ↔ ∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ ∅))) | |
3 | 1, 2 | mpan2 687 | . . . . 5 ⊢ (𝑋 ∈ 𝑉 → (𝑥 ∈ (𝑋 ↾t ∅) ↔ ∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ ∅))) |
4 | in0 4342 | . . . . . . . . 9 ⊢ (𝑦 ∩ ∅) = ∅ | |
5 | 4 | eqeq2i 2831 | . . . . . . . 8 ⊢ (𝑥 = (𝑦 ∩ ∅) ↔ 𝑥 = ∅) |
6 | 5 | rexbii 3244 | . . . . . . 7 ⊢ (∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ ∅) ↔ ∃𝑦 ∈ 𝑋 𝑥 = ∅) |
7 | df-rex 3141 | . . . . . . . 8 ⊢ (∃𝑦 ∈ 𝑋 𝑥 = ∅ ↔ ∃𝑦(𝑦 ∈ 𝑋 ∧ 𝑥 = ∅)) | |
8 | 19.41v 1941 | . . . . . . . . 9 ⊢ (∃𝑦(𝑦 ∈ 𝑋 ∧ 𝑥 = ∅) ↔ (∃𝑦 𝑦 ∈ 𝑋 ∧ 𝑥 = ∅)) | |
9 | n0 4307 | . . . . . . . . . . 11 ⊢ (𝑋 ≠ ∅ ↔ ∃𝑦 𝑦 ∈ 𝑋) | |
10 | 9 | bicomi 225 | . . . . . . . . . 10 ⊢ (∃𝑦 𝑦 ∈ 𝑋 ↔ 𝑋 ≠ ∅) |
11 | 10 | anbi1i 623 | . . . . . . . . 9 ⊢ ((∃𝑦 𝑦 ∈ 𝑋 ∧ 𝑥 = ∅) ↔ (𝑋 ≠ ∅ ∧ 𝑥 = ∅)) |
12 | 8, 11 | bitri 276 | . . . . . . . 8 ⊢ (∃𝑦(𝑦 ∈ 𝑋 ∧ 𝑥 = ∅) ↔ (𝑋 ≠ ∅ ∧ 𝑥 = ∅)) |
13 | 7, 12 | bitri 276 | . . . . . . 7 ⊢ (∃𝑦 ∈ 𝑋 𝑥 = ∅ ↔ (𝑋 ≠ ∅ ∧ 𝑥 = ∅)) |
14 | 6, 13 | bitri 276 | . . . . . 6 ⊢ (∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ ∅) ↔ (𝑋 ≠ ∅ ∧ 𝑥 = ∅)) |
15 | 14 | baib 536 | . . . . 5 ⊢ (𝑋 ≠ ∅ → (∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ ∅) ↔ 𝑥 = ∅)) |
16 | 3, 15 | sylan9bb 510 | . . . 4 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝑋 ≠ ∅) → (𝑥 ∈ (𝑋 ↾t ∅) ↔ 𝑥 = ∅)) |
17 | velsn 4573 | . . . 4 ⊢ (𝑥 ∈ {∅} ↔ 𝑥 = ∅) | |
18 | 16, 17 | syl6bbr 290 | . . 3 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝑋 ≠ ∅) → (𝑥 ∈ (𝑋 ↾t ∅) ↔ 𝑥 ∈ {∅})) |
19 | 18 | eqrdv 2816 | . 2 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝑋 ≠ ∅) → (𝑋 ↾t ∅) = {∅}) |
20 | 19 | ex 413 | 1 ⊢ (𝑋 ∈ 𝑉 → (𝑋 ≠ ∅ → (𝑋 ↾t ∅) = {∅})) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 207 ∧ wa 396 = wceq 1528 ∃wex 1771 ∈ wcel 2105 ≠ wne 3013 ∃wrex 3136 Vcvv 3492 ∩ cin 3932 ∅c0 4288 {csn 4557 (class class class)co 7145 ↾t crest 16682 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1787 ax-4 1801 ax-5 1902 ax-6 1961 ax-7 2006 ax-8 2107 ax-9 2115 ax-10 2136 ax-11 2151 ax-12 2167 ax-ext 2790 ax-rep 5181 ax-sep 5194 ax-nul 5201 ax-pr 5320 ax-un 7450 |
This theorem depends on definitions: df-bi 208 df-an 397 df-or 842 df-3an 1081 df-tru 1531 df-ex 1772 df-nf 1776 df-sb 2061 df-mo 2615 df-eu 2647 df-clab 2797 df-cleq 2811 df-clel 2890 df-nfc 2960 df-ne 3014 df-ral 3140 df-rex 3141 df-reu 3142 df-rab 3144 df-v 3494 df-sbc 3770 df-csb 3881 df-dif 3936 df-un 3938 df-in 3940 df-ss 3949 df-nul 4289 df-if 4464 df-sn 4558 df-pr 4560 df-op 4564 df-uni 4831 df-iun 4912 df-br 5058 df-opab 5120 df-mpt 5138 df-id 5453 df-xp 5554 df-rel 5555 df-cnv 5556 df-co 5557 df-dm 5558 df-rn 5559 df-res 5560 df-ima 5561 df-iota 6307 df-fun 6350 df-fn 6351 df-f 6352 df-f1 6353 df-fo 6354 df-f1o 6355 df-fv 6356 df-ov 7148 df-oprab 7149 df-mpo 7150 df-rest 16684 |
This theorem is referenced by: bj-rest10b 34274 |
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