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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 12351 | . . . 4 ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑥 ∈ 𝑋 ∧ 𝑦 ∈ 𝑋) → (𝑥𝐷𝑦) = (𝑦𝐷𝑥)) | |
2 | 1 | 3expb 1163 | . . 3 ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ (𝑥 ∈ 𝑋 ∧ 𝑦 ∈ 𝑋)) → (𝑥𝐷𝑦) = (𝑦𝐷𝑥)) |
3 | 2 | ralrimivva 2486 | . 2 ⊢ (𝐷 ∈ (∞Met‘𝑋) → ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 (𝑥𝐷𝑦) = (𝑦𝐷𝑥)) |
4 | xmetf 12333 | . . 3 ⊢ (𝐷 ∈ (∞Met‘𝑋) → 𝐷:(𝑋 × 𝑋)⟶ℝ*) | |
5 | ffn 5228 | . . 3 ⊢ (𝐷:(𝑋 × 𝑋)⟶ℝ* → 𝐷 Fn (𝑋 × 𝑋)) | |
6 | tpossym 6125 | . . 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 166 | 1 ⊢ (𝐷 ∈ (∞Met‘𝑋) → tpos 𝐷 = 𝐷) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ↔ wb 104 = wceq 1312 ∈ wcel 1461 ∀wral 2388 × cxp 4495 Fn wfn 5074 ⟶wf 5075 ‘cfv 5079 (class class class)co 5726 tpos ctpos 6093 ℝ*cxr 7717 ∞Metcxmet 11986 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 586 ax-in2 587 ax-io 681 ax-5 1404 ax-7 1405 ax-gen 1406 ax-ie1 1450 ax-ie2 1451 ax-8 1463 ax-10 1464 ax-11 1465 ax-i12 1466 ax-bndl 1467 ax-4 1468 ax-13 1472 ax-14 1473 ax-17 1487 ax-i9 1491 ax-ial 1495 ax-i5r 1496 ax-ext 2095 ax-sep 4004 ax-nul 4012 ax-pow 4056 ax-pr 4089 ax-un 4313 ax-setind 4410 ax-cnex 7630 ax-resscn 7631 ax-1re 7633 ax-addrcl 7636 ax-0id 7647 ax-rnegex 7648 ax-pre-ltirr 7651 ax-pre-apti 7654 |
This theorem depends on definitions: df-bi 116 df-dc 803 df-3or 944 df-3an 945 df-tru 1315 df-fal 1318 df-nf 1418 df-sb 1717 df-eu 1976 df-mo 1977 df-clab 2100 df-cleq 2106 df-clel 2109 df-nfc 2242 df-ne 2281 df-nel 2376 df-ral 2393 df-rex 2394 df-rab 2397 df-v 2657 df-sbc 2877 df-csb 2970 df-dif 3037 df-un 3039 df-in 3041 df-ss 3048 df-nul 3328 df-if 3439 df-pw 3476 df-sn 3497 df-pr 3498 df-op 3500 df-uni 3701 df-iun 3779 df-br 3894 df-opab 3948 df-mpt 3949 df-id 4173 df-xp 4503 df-rel 4504 df-cnv 4505 df-co 4506 df-dm 4507 df-rn 4508 df-res 4509 df-ima 4510 df-iota 5044 df-fun 5081 df-fn 5082 df-f 5083 df-fo 5085 df-fv 5087 df-ov 5729 df-oprab 5730 df-mpo 5731 df-1st 5990 df-2nd 5991 df-tpos 6094 df-map 6496 df-pnf 7720 df-mnf 7721 df-xr 7722 df-ltxr 7723 df-le 7724 df-xadd 9447 df-xmet 11994 |
This theorem is referenced by: (None) |
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