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| Mirrors > Home > ILE Home > Th. List > opnneissb | GIF version | ||
| Description: An open set is a neighborhood of any of its subsets. (Contributed by FL, 2-Oct-2006.) |
| Ref | Expression |
|---|---|
| neips.1 | ⊢ 𝑋 = ∪ 𝐽 |
| Ref | Expression |
|---|---|
| opnneissb | ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑋) → (𝑆 ⊆ 𝑁 ↔ 𝑁 ∈ ((nei‘𝐽)‘𝑆))) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | neips.1 | . . . . . . 7 ⊢ 𝑋 = ∪ 𝐽 | |
| 2 | 1 | eltopss 14481 | . . . . . 6 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽) → 𝑁 ⊆ 𝑋) |
| 3 | 2 | adantr 276 | . . . . 5 ⊢ (((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽) ∧ (𝑆 ⊆ 𝑋 ∧ 𝑆 ⊆ 𝑁)) → 𝑁 ⊆ 𝑋) |
| 4 | ssid 3213 | . . . . . . 7 ⊢ 𝑁 ⊆ 𝑁 | |
| 5 | sseq2 3217 | . . . . . . . . 9 ⊢ (𝑔 = 𝑁 → (𝑆 ⊆ 𝑔 ↔ 𝑆 ⊆ 𝑁)) | |
| 6 | sseq1 3216 | . . . . . . . . 9 ⊢ (𝑔 = 𝑁 → (𝑔 ⊆ 𝑁 ↔ 𝑁 ⊆ 𝑁)) | |
| 7 | 5, 6 | anbi12d 473 | . . . . . . . 8 ⊢ (𝑔 = 𝑁 → ((𝑆 ⊆ 𝑔 ∧ 𝑔 ⊆ 𝑁) ↔ (𝑆 ⊆ 𝑁 ∧ 𝑁 ⊆ 𝑁))) |
| 8 | 7 | rspcev 2877 | . . . . . . 7 ⊢ ((𝑁 ∈ 𝐽 ∧ (𝑆 ⊆ 𝑁 ∧ 𝑁 ⊆ 𝑁)) → ∃𝑔 ∈ 𝐽 (𝑆 ⊆ 𝑔 ∧ 𝑔 ⊆ 𝑁)) |
| 9 | 4, 8 | mpanr2 438 | . . . . . 6 ⊢ ((𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑁) → ∃𝑔 ∈ 𝐽 (𝑆 ⊆ 𝑔 ∧ 𝑔 ⊆ 𝑁)) |
| 10 | 9 | ad2ant2l 508 | . . . . 5 ⊢ (((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽) ∧ (𝑆 ⊆ 𝑋 ∧ 𝑆 ⊆ 𝑁)) → ∃𝑔 ∈ 𝐽 (𝑆 ⊆ 𝑔 ∧ 𝑔 ⊆ 𝑁)) |
| 11 | 1 | isnei 14616 | . . . . . 6 ⊢ ((𝐽 ∈ Top ∧ 𝑆 ⊆ 𝑋) → (𝑁 ∈ ((nei‘𝐽)‘𝑆) ↔ (𝑁 ⊆ 𝑋 ∧ ∃𝑔 ∈ 𝐽 (𝑆 ⊆ 𝑔 ∧ 𝑔 ⊆ 𝑁)))) |
| 12 | 11 | ad2ant2r 509 | . . . . 5 ⊢ (((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽) ∧ (𝑆 ⊆ 𝑋 ∧ 𝑆 ⊆ 𝑁)) → (𝑁 ∈ ((nei‘𝐽)‘𝑆) ↔ (𝑁 ⊆ 𝑋 ∧ ∃𝑔 ∈ 𝐽 (𝑆 ⊆ 𝑔 ∧ 𝑔 ⊆ 𝑁)))) |
| 13 | 3, 10, 12 | mpbir2and 947 | . . . 4 ⊢ (((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽) ∧ (𝑆 ⊆ 𝑋 ∧ 𝑆 ⊆ 𝑁)) → 𝑁 ∈ ((nei‘𝐽)‘𝑆)) |
| 14 | 13 | exp43 372 | . . 3 ⊢ (𝐽 ∈ Top → (𝑁 ∈ 𝐽 → (𝑆 ⊆ 𝑋 → (𝑆 ⊆ 𝑁 → 𝑁 ∈ ((nei‘𝐽)‘𝑆))))) |
| 15 | 14 | 3imp 1196 | . 2 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑋) → (𝑆 ⊆ 𝑁 → 𝑁 ∈ ((nei‘𝐽)‘𝑆))) |
| 16 | ssnei 14623 | . . . 4 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ ((nei‘𝐽)‘𝑆)) → 𝑆 ⊆ 𝑁) | |
| 17 | 16 | ex 115 | . . 3 ⊢ (𝐽 ∈ Top → (𝑁 ∈ ((nei‘𝐽)‘𝑆) → 𝑆 ⊆ 𝑁)) |
| 18 | 17 | 3ad2ant1 1021 | . 2 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑋) → (𝑁 ∈ ((nei‘𝐽)‘𝑆) → 𝑆 ⊆ 𝑁)) |
| 19 | 15, 18 | impbid 129 | 1 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑋) → (𝑆 ⊆ 𝑁 ↔ 𝑁 ∈ ((nei‘𝐽)‘𝑆))) |
| Colors of variables: wff set class |
| Syntax hints: → wi 4 ∧ wa 104 ↔ wb 105 ∧ w3a 981 = wceq 1373 ∈ wcel 2176 ∃wrex 2485 ⊆ wss 3166 ∪ cuni 3850 ‘cfv 5271 Topctop 14469 neicnei 14610 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-io 711 ax-5 1470 ax-7 1471 ax-gen 1472 ax-ie1 1516 ax-ie2 1517 ax-8 1527 ax-10 1528 ax-11 1529 ax-i12 1530 ax-bndl 1532 ax-4 1533 ax-17 1549 ax-i9 1553 ax-ial 1557 ax-i5r 1558 ax-14 2179 ax-ext 2187 ax-coll 4159 ax-sep 4162 ax-pow 4218 ax-pr 4253 |
| This theorem depends on definitions: df-bi 117 df-3an 983 df-tru 1376 df-nf 1484 df-sb 1786 df-eu 2057 df-mo 2058 df-clab 2192 df-cleq 2198 df-clel 2201 df-nfc 2337 df-ral 2489 df-rex 2490 df-reu 2491 df-rab 2493 df-v 2774 df-sbc 2999 df-csb 3094 df-un 3170 df-in 3172 df-ss 3179 df-pw 3618 df-sn 3639 df-pr 3640 df-op 3642 df-uni 3851 df-iun 3929 df-br 4045 df-opab 4106 df-mpt 4107 df-id 4340 df-xp 4681 df-rel 4682 df-cnv 4683 df-co 4684 df-dm 4685 df-rn 4686 df-res 4687 df-ima 4688 df-iota 5232 df-fun 5273 df-fn 5274 df-f 5275 df-f1 5276 df-fo 5277 df-f1o 5278 df-fv 5279 df-top 14470 df-nei 14611 |
| This theorem is referenced by: opnneiss 14630 |
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