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Mirrors > Home > ILE Home > Th. List > xmettpos | GIF version |
Description: The distance function of an extended metric space is symmetric. (Contributed by Mario Carneiro, 20-Aug-2015.) |
Ref | Expression |
---|---|
xmettpos | ⊢ (𝐷 ∈ (∞Met‘𝑋) → tpos 𝐷 = 𝐷) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | xmetsym 14221 | . . . 4 ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑥 ∈ 𝑋 ∧ 𝑦 ∈ 𝑋) → (𝑥𝐷𝑦) = (𝑦𝐷𝑥)) | |
2 | 1 | 3expb 1205 | . . 3 ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ (𝑥 ∈ 𝑋 ∧ 𝑦 ∈ 𝑋)) → (𝑥𝐷𝑦) = (𝑦𝐷𝑥)) |
3 | 2 | ralrimivva 2569 | . 2 ⊢ (𝐷 ∈ (∞Met‘𝑋) → ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 (𝑥𝐷𝑦) = (𝑦𝐷𝑥)) |
4 | xmetf 14203 | . . 3 ⊢ (𝐷 ∈ (∞Met‘𝑋) → 𝐷:(𝑋 × 𝑋)⟶ℝ*) | |
5 | ffn 5377 | . . 3 ⊢ (𝐷:(𝑋 × 𝑋)⟶ℝ* → 𝐷 Fn (𝑋 × 𝑋)) | |
6 | tpossym 6291 | . . 3 ⊢ (𝐷 Fn (𝑋 × 𝑋) → (tpos 𝐷 = 𝐷 ↔ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 (𝑥𝐷𝑦) = (𝑦𝐷𝑥))) | |
7 | 4, 5, 6 | 3syl 17 | . 2 ⊢ (𝐷 ∈ (∞Met‘𝑋) → (tpos 𝐷 = 𝐷 ↔ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 (𝑥𝐷𝑦) = (𝑦𝐷𝑥))) |
8 | 3, 7 | mpbird 167 | 1 ⊢ (𝐷 ∈ (∞Met‘𝑋) → tpos 𝐷 = 𝐷) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ↔ wb 105 = wceq 1363 ∈ wcel 2158 ∀wral 2465 × cxp 4636 Fn wfn 5223 ⟶wf 5224 ‘cfv 5228 (class class class)co 5888 tpos ctpos 6259 ℝ*cxr 8005 ∞Metcxmet 13779 |
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-in1 615 ax-in2 616 ax-io 710 ax-5 1457 ax-7 1458 ax-gen 1459 ax-ie1 1503 ax-ie2 1504 ax-8 1514 ax-10 1515 ax-11 1516 ax-i12 1517 ax-bndl 1519 ax-4 1520 ax-17 1536 ax-i9 1540 ax-ial 1544 ax-i5r 1545 ax-13 2160 ax-14 2161 ax-ext 2169 ax-sep 4133 ax-nul 4141 ax-pow 4186 ax-pr 4221 ax-un 4445 ax-setind 4548 ax-cnex 7916 ax-resscn 7917 ax-1re 7919 ax-addrcl 7922 ax-0id 7933 ax-rnegex 7934 ax-pre-ltirr 7937 ax-pre-apti 7940 |
This theorem depends on definitions: df-bi 117 df-dc 836 df-3or 980 df-3an 981 df-tru 1366 df-fal 1369 df-nf 1471 df-sb 1773 df-eu 2039 df-mo 2040 df-clab 2174 df-cleq 2180 df-clel 2183 df-nfc 2318 df-ne 2358 df-nel 2453 df-ral 2470 df-rex 2471 df-rab 2474 df-v 2751 df-sbc 2975 df-csb 3070 df-dif 3143 df-un 3145 df-in 3147 df-ss 3154 df-nul 3435 df-if 3547 df-pw 3589 df-sn 3610 df-pr 3611 df-op 3613 df-uni 3822 df-iun 3900 df-br 4016 df-opab 4077 df-mpt 4078 df-id 4305 df-xp 4644 df-rel 4645 df-cnv 4646 df-co 4647 df-dm 4648 df-rn 4649 df-res 4650 df-ima 4651 df-iota 5190 df-fun 5230 df-fn 5231 df-f 5232 df-fo 5234 df-fv 5236 df-ov 5891 df-oprab 5892 df-mpo 5893 df-1st 6155 df-2nd 6156 df-tpos 6260 df-map 6664 df-pnf 8008 df-mnf 8009 df-xr 8010 df-ltxr 8011 df-le 8012 df-xadd 9787 df-xmet 13787 |
This theorem is referenced by: (None) |
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