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Mirrors > Home > MPE Home > Th. List > Mathboxes > opnrebl | Structured version Visualization version GIF version |
Description: A set is open in the standard topology of the reals precisely when every point can be enclosed in an open ball. (Contributed by Jeff Hankins, 23-Sep-2013.) (Proof shortened by Mario Carneiro, 30-Jan-2014.) |
Ref | Expression |
---|---|
opnrebl | ⊢ (𝐴 ∈ (topGen‘ran (,)) ↔ (𝐴 ⊆ ℝ ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ ((𝑥 − 𝑦)(,)(𝑥 + 𝑦)) ⊆ 𝐴)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqid 2821 | . . . 4 ⊢ ((abs ∘ − ) ↾ (ℝ × ℝ)) = ((abs ∘ − ) ↾ (ℝ × ℝ)) | |
2 | 1 | rexmet 23393 | . . 3 ⊢ ((abs ∘ − ) ↾ (ℝ × ℝ)) ∈ (∞Met‘ℝ) |
3 | eqid 2821 | . . . . 5 ⊢ (MetOpen‘((abs ∘ − ) ↾ (ℝ × ℝ))) = (MetOpen‘((abs ∘ − ) ↾ (ℝ × ℝ))) | |
4 | 1, 3 | tgioo 23398 | . . . 4 ⊢ (topGen‘ran (,)) = (MetOpen‘((abs ∘ − ) ↾ (ℝ × ℝ))) |
5 | 4 | elmopn2 23049 | . . 3 ⊢ (((abs ∘ − ) ↾ (ℝ × ℝ)) ∈ (∞Met‘ℝ) → (𝐴 ∈ (topGen‘ran (,)) ↔ (𝐴 ⊆ ℝ ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) ⊆ 𝐴))) |
6 | 2, 5 | ax-mp 5 | . 2 ⊢ (𝐴 ∈ (topGen‘ran (,)) ↔ (𝐴 ⊆ ℝ ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) ⊆ 𝐴)) |
7 | ssel2 3961 | . . . . 5 ⊢ ((𝐴 ⊆ ℝ ∧ 𝑥 ∈ 𝐴) → 𝑥 ∈ ℝ) | |
8 | rpre 12391 | . . . . . . . 8 ⊢ (𝑦 ∈ ℝ+ → 𝑦 ∈ ℝ) | |
9 | 1 | bl2ioo 23394 | . . . . . . . 8 ⊢ ((𝑥 ∈ ℝ ∧ 𝑦 ∈ ℝ) → (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) = ((𝑥 − 𝑦)(,)(𝑥 + 𝑦))) |
10 | 8, 9 | sylan2 594 | . . . . . . 7 ⊢ ((𝑥 ∈ ℝ ∧ 𝑦 ∈ ℝ+) → (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) = ((𝑥 − 𝑦)(,)(𝑥 + 𝑦))) |
11 | 10 | sseq1d 3997 | . . . . . 6 ⊢ ((𝑥 ∈ ℝ ∧ 𝑦 ∈ ℝ+) → ((𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) ⊆ 𝐴 ↔ ((𝑥 − 𝑦)(,)(𝑥 + 𝑦)) ⊆ 𝐴)) |
12 | 11 | rexbidva 3296 | . . . . 5 ⊢ (𝑥 ∈ ℝ → (∃𝑦 ∈ ℝ+ (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) ⊆ 𝐴 ↔ ∃𝑦 ∈ ℝ+ ((𝑥 − 𝑦)(,)(𝑥 + 𝑦)) ⊆ 𝐴)) |
13 | 7, 12 | syl 17 | . . . 4 ⊢ ((𝐴 ⊆ ℝ ∧ 𝑥 ∈ 𝐴) → (∃𝑦 ∈ ℝ+ (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) ⊆ 𝐴 ↔ ∃𝑦 ∈ ℝ+ ((𝑥 − 𝑦)(,)(𝑥 + 𝑦)) ⊆ 𝐴)) |
14 | 13 | ralbidva 3196 | . . 3 ⊢ (𝐴 ⊆ ℝ → (∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) ⊆ 𝐴 ↔ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ ((𝑥 − 𝑦)(,)(𝑥 + 𝑦)) ⊆ 𝐴)) |
15 | 14 | pm5.32i 577 | . 2 ⊢ ((𝐴 ⊆ ℝ ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ (𝑥(ball‘((abs ∘ − ) ↾ (ℝ × ℝ)))𝑦) ⊆ 𝐴) ↔ (𝐴 ⊆ ℝ ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ ((𝑥 − 𝑦)(,)(𝑥 + 𝑦)) ⊆ 𝐴)) |
16 | 6, 15 | bitri 277 | 1 ⊢ (𝐴 ∈ (topGen‘ran (,)) ↔ (𝐴 ⊆ ℝ ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ ℝ+ ((𝑥 − 𝑦)(,)(𝑥 + 𝑦)) ⊆ 𝐴)) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 208 ∧ wa 398 = wceq 1533 ∈ wcel 2110 ∀wral 3138 ∃wrex 3139 ⊆ wss 3935 × cxp 5547 ran crn 5550 ↾ cres 5551 ∘ ccom 5553 ‘cfv 6349 (class class class)co 7150 ℝcr 10530 + caddc 10534 − cmin 10864 ℝ+crp 12383 (,)cioo 12732 abscabs 14587 topGenctg 16705 ∞Metcxmet 20524 ballcbl 20526 MetOpencmopn 20529 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1907 ax-6 1966 ax-7 2011 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2157 ax-12 2173 ax-ext 2793 ax-sep 5195 ax-nul 5202 ax-pow 5258 ax-pr 5321 ax-un 7455 ax-cnex 10587 ax-resscn 10588 ax-1cn 10589 ax-icn 10590 ax-addcl 10591 ax-addrcl 10592 ax-mulcl 10593 ax-mulrcl 10594 ax-mulcom 10595 ax-addass 10596 ax-mulass 10597 ax-distr 10598 ax-i2m1 10599 ax-1ne0 10600 ax-1rid 10601 ax-rnegex 10602 ax-rrecex 10603 ax-cnre 10604 ax-pre-lttri 10605 ax-pre-lttrn 10606 ax-pre-ltadd 10607 ax-pre-mulgt0 10608 ax-pre-sup 10609 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1536 df-ex 1777 df-nf 1781 df-sb 2066 df-mo 2618 df-eu 2650 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rmo 3146 df-rab 3147 df-v 3496 df-sbc 3772 df-csb 3883 df-dif 3938 df-un 3940 df-in 3942 df-ss 3951 df-pss 3953 df-nul 4291 df-if 4467 df-pw 4540 df-sn 4561 df-pr 4563 df-tp 4565 df-op 4567 df-uni 4832 df-iun 4913 df-br 5059 df-opab 5121 df-mpt 5139 df-tr 5165 df-id 5454 df-eprel 5459 df-po 5468 df-so 5469 df-fr 5508 df-we 5510 df-xp 5555 df-rel 5556 df-cnv 5557 df-co 5558 df-dm 5559 df-rn 5560 df-res 5561 df-ima 5562 df-pred 6142 df-ord 6188 df-on 6189 df-lim 6190 df-suc 6191 df-iota 6308 df-fun 6351 df-fn 6352 df-f 6353 df-f1 6354 df-fo 6355 df-f1o 6356 df-fv 6357 df-riota 7108 df-ov 7153 df-oprab 7154 df-mpo 7155 df-om 7575 df-1st 7683 df-2nd 7684 df-wrecs 7941 df-recs 8002 df-rdg 8040 df-er 8283 df-map 8402 df-en 8504 df-dom 8505 df-sdom 8506 df-sup 8900 df-inf 8901 df-pnf 10671 df-mnf 10672 df-xr 10673 df-ltxr 10674 df-le 10675 df-sub 10866 df-neg 10867 df-div 11292 df-nn 11633 df-2 11694 df-3 11695 df-n0 11892 df-z 11976 df-uz 12238 df-q 12343 df-rp 12384 df-xneg 12501 df-xadd 12502 df-xmul 12503 df-ioo 12736 df-seq 13364 df-exp 13424 df-cj 14452 df-re 14453 df-im 14454 df-sqrt 14588 df-abs 14589 df-topgen 16711 df-psmet 20531 df-xmet 20532 df-met 20533 df-bl 20534 df-mopn 20535 df-bases 21548 |
This theorem is referenced by: (None) |
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