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Mirrors > Home > MPE Home > Th. List > opnneiss | Structured version Visualization version GIF version |
Description: An open set is a neighborhood of any of its subsets. (Contributed by NM, 13-Feb-2007.) |
Ref | Expression |
---|---|
opnneiss | ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑁) → 𝑁 ∈ ((nei‘𝐽)‘𝑆)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | simp3 1140 | . 2 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑁) → 𝑆 ⊆ 𝑁) | |
2 | eqid 2738 | . . . . 5 ⊢ ∪ 𝐽 = ∪ 𝐽 | |
3 | 2 | eltopss 21828 | . . . 4 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽) → 𝑁 ⊆ ∪ 𝐽) |
4 | sstr 3923 | . . . . 5 ⊢ ((𝑆 ⊆ 𝑁 ∧ 𝑁 ⊆ ∪ 𝐽) → 𝑆 ⊆ ∪ 𝐽) | |
5 | 4 | ancoms 462 | . . . 4 ⊢ ((𝑁 ⊆ ∪ 𝐽 ∧ 𝑆 ⊆ 𝑁) → 𝑆 ⊆ ∪ 𝐽) |
6 | 3, 5 | stoic3 1784 | . . 3 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑁) → 𝑆 ⊆ ∪ 𝐽) |
7 | 2 | opnneissb 22035 | . . 3 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ ∪ 𝐽) → (𝑆 ⊆ 𝑁 ↔ 𝑁 ∈ ((nei‘𝐽)‘𝑆))) |
8 | 6, 7 | syld3an3 1411 | . 2 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑁) → (𝑆 ⊆ 𝑁 ↔ 𝑁 ∈ ((nei‘𝐽)‘𝑆))) |
9 | 1, 8 | mpbid 235 | 1 ⊢ ((𝐽 ∈ Top ∧ 𝑁 ∈ 𝐽 ∧ 𝑆 ⊆ 𝑁) → 𝑁 ∈ ((nei‘𝐽)‘𝑆)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 209 ∧ w3a 1089 ∈ wcel 2111 ⊆ wss 3880 ∪ cuni 4833 ‘cfv 6397 Topctop 21814 neicnei 22018 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1803 ax-4 1817 ax-5 1918 ax-6 1976 ax-7 2016 ax-8 2113 ax-9 2121 ax-10 2142 ax-11 2159 ax-12 2176 ax-ext 2709 ax-rep 5193 ax-sep 5206 ax-nul 5213 ax-pow 5272 ax-pr 5336 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 848 df-3an 1091 df-tru 1546 df-fal 1556 df-ex 1788 df-nf 1792 df-sb 2072 df-mo 2540 df-eu 2569 df-clab 2716 df-cleq 2730 df-clel 2817 df-nfc 2887 df-ne 2942 df-ral 3067 df-rex 3068 df-reu 3069 df-rab 3071 df-v 3422 df-sbc 3709 df-csb 3826 df-dif 3883 df-un 3885 df-in 3887 df-ss 3897 df-nul 4252 df-if 4454 df-pw 4529 df-sn 4556 df-pr 4558 df-op 4562 df-uni 4834 df-iun 4920 df-br 5068 df-opab 5130 df-mpt 5150 df-id 5469 df-xp 5571 df-rel 5572 df-cnv 5573 df-co 5574 df-dm 5575 df-rn 5576 df-res 5577 df-ima 5578 df-iota 6355 df-fun 6399 df-fn 6400 df-f 6401 df-f1 6402 df-fo 6403 df-f1o 6404 df-fv 6405 df-top 21815 df-nei 22019 |
This theorem is referenced by: opnneip 22040 tpnei 22042 topssnei 22045 opnneiid 22047 neissex 22048 cmpkgen 22472 opnneir 45901 |
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