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Mirrors > Home > MPE Home > Th. List > Mathboxes > bj-restn0 | Structured version Visualization version GIF version |
Description: An elementwise intersection on a nonempty family is nonempty. (Contributed by BJ, 27-Apr-2021.) |
Ref | Expression |
---|---|
bj-restn0 | ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (𝑋 ≠ ∅ → (𝑋 ↾t 𝐴) ≠ ∅)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | n0 4308 | . . . 4 ⊢ (𝑋 ≠ ∅ ↔ ∃𝑦 𝑦 ∈ 𝑋) | |
2 | vex 3496 | . . . . . . . . . . 11 ⊢ 𝑦 ∈ V | |
3 | 2 | inex1 5212 | . . . . . . . . . 10 ⊢ (𝑦 ∩ 𝐴) ∈ V |
4 | 3 | isseti 3507 | . . . . . . . . 9 ⊢ ∃𝑥 𝑥 = (𝑦 ∩ 𝐴) |
5 | 4 | jctr 527 | . . . . . . . 8 ⊢ (𝑦 ∈ 𝑋 → (𝑦 ∈ 𝑋 ∧ ∃𝑥 𝑥 = (𝑦 ∩ 𝐴))) |
6 | 5 | eximi 1829 | . . . . . . 7 ⊢ (∃𝑦 𝑦 ∈ 𝑋 → ∃𝑦(𝑦 ∈ 𝑋 ∧ ∃𝑥 𝑥 = (𝑦 ∩ 𝐴))) |
7 | df-rex 3142 | . . . . . . 7 ⊢ (∃𝑦 ∈ 𝑋 ∃𝑥 𝑥 = (𝑦 ∩ 𝐴) ↔ ∃𝑦(𝑦 ∈ 𝑋 ∧ ∃𝑥 𝑥 = (𝑦 ∩ 𝐴))) | |
8 | 6, 7 | sylibr 236 | . . . . . 6 ⊢ (∃𝑦 𝑦 ∈ 𝑋 → ∃𝑦 ∈ 𝑋 ∃𝑥 𝑥 = (𝑦 ∩ 𝐴)) |
9 | rexcom4 3247 | . . . . . 6 ⊢ (∃𝑦 ∈ 𝑋 ∃𝑥 𝑥 = (𝑦 ∩ 𝐴) ↔ ∃𝑥∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ 𝐴)) | |
10 | 8, 9 | sylib 220 | . . . . 5 ⊢ (∃𝑦 𝑦 ∈ 𝑋 → ∃𝑥∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ 𝐴)) |
11 | 10 | a1i 11 | . . . 4 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (∃𝑦 𝑦 ∈ 𝑋 → ∃𝑥∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ 𝐴))) |
12 | 1, 11 | syl5bi 244 | . . 3 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (𝑋 ≠ ∅ → ∃𝑥∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ 𝐴))) |
13 | elrest 16693 | . . . . 5 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (𝑥 ∈ (𝑋 ↾t 𝐴) ↔ ∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ 𝐴))) | |
14 | 13 | biimprd 250 | . . . 4 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ 𝐴) → 𝑥 ∈ (𝑋 ↾t 𝐴))) |
15 | 14 | eximdv 1912 | . . 3 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (∃𝑥∃𝑦 ∈ 𝑋 𝑥 = (𝑦 ∩ 𝐴) → ∃𝑥 𝑥 ∈ (𝑋 ↾t 𝐴))) |
16 | 12, 15 | syld 47 | . 2 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (𝑋 ≠ ∅ → ∃𝑥 𝑥 ∈ (𝑋 ↾t 𝐴))) |
17 | n0 4308 | . 2 ⊢ ((𝑋 ↾t 𝐴) ≠ ∅ ↔ ∃𝑥 𝑥 ∈ (𝑋 ↾t 𝐴)) | |
18 | 16, 17 | syl6ibr 254 | 1 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (𝑋 ≠ ∅ → (𝑋 ↾t 𝐴) ≠ ∅)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 398 = wceq 1531 ∃wex 1774 ∈ wcel 2108 ≠ wne 3014 ∃wrex 3137 ∩ cin 3933 ∅c0 4289 (class class class)co 7148 ↾t crest 16686 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1905 ax-6 1964 ax-7 2009 ax-8 2110 ax-9 2118 ax-10 2139 ax-11 2154 ax-12 2170 ax-ext 2791 ax-rep 5181 ax-sep 5194 ax-nul 5201 ax-pr 5320 ax-un 7453 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3an 1084 df-tru 1534 df-ex 1775 df-nf 1779 df-sb 2064 df-mo 2616 df-eu 2648 df-clab 2798 df-cleq 2812 df-clel 2891 df-nfc 2961 df-ne 3015 df-ral 3141 df-rex 3142 df-reu 3143 df-rab 3145 df-v 3495 df-sbc 3771 df-csb 3882 df-dif 3937 df-un 3939 df-in 3941 df-ss 3950 df-nul 4290 df-if 4466 df-sn 4560 df-pr 4562 df-op 4566 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 7151 df-oprab 7152 df-mpo 7153 df-rest 16688 |
This theorem is referenced by: bj-restn0b 34374 |
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