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Mirrors > Home > ILE Home > Th. List > metres | GIF version |
Description: A restriction of a metric is a metric. (Contributed by NM, 26-Aug-2007.) (Revised by Mario Carneiro, 14-Aug-2015.) |
Ref | Expression |
---|---|
metres | ⊢ (𝐷 ∈ (Met‘𝑋) → (𝐷 ↾ (𝑅 × 𝑅)) ∈ (Met‘(𝑋 ∩ 𝑅))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | metf 12847 | . . 3 ⊢ (𝐷 ∈ (Met‘𝑋) → 𝐷:(𝑋 × 𝑋)⟶ℝ) | |
2 | fdm 5328 | . . 3 ⊢ (𝐷:(𝑋 × 𝑋)⟶ℝ → dom 𝐷 = (𝑋 × 𝑋)) | |
3 | metreslem 12876 | . . 3 ⊢ (dom 𝐷 = (𝑋 × 𝑋) → (𝐷 ↾ (𝑅 × 𝑅)) = (𝐷 ↾ ((𝑋 ∩ 𝑅) × (𝑋 ∩ 𝑅)))) | |
4 | 1, 2, 3 | 3syl 17 | . 2 ⊢ (𝐷 ∈ (Met‘𝑋) → (𝐷 ↾ (𝑅 × 𝑅)) = (𝐷 ↾ ((𝑋 ∩ 𝑅) × (𝑋 ∩ 𝑅)))) |
5 | inss1 3328 | . . 3 ⊢ (𝑋 ∩ 𝑅) ⊆ 𝑋 | |
6 | metres2 12877 | . . 3 ⊢ ((𝐷 ∈ (Met‘𝑋) ∧ (𝑋 ∩ 𝑅) ⊆ 𝑋) → (𝐷 ↾ ((𝑋 ∩ 𝑅) × (𝑋 ∩ 𝑅))) ∈ (Met‘(𝑋 ∩ 𝑅))) | |
7 | 5, 6 | mpan2 422 | . 2 ⊢ (𝐷 ∈ (Met‘𝑋) → (𝐷 ↾ ((𝑋 ∩ 𝑅) × (𝑋 ∩ 𝑅))) ∈ (Met‘(𝑋 ∩ 𝑅))) |
8 | 4, 7 | eqeltrd 2234 | 1 ⊢ (𝐷 ∈ (Met‘𝑋) → (𝐷 ↾ (𝑅 × 𝑅)) ∈ (Met‘(𝑋 ∩ 𝑅))) |
Colors of variables: wff set class |
Syntax hints: → wi 4 = wceq 1335 ∈ wcel 2128 ∩ cin 3101 ⊆ wss 3102 × cxp 4587 dom cdm 4589 ↾ cres 4591 ⟶wf 5169 ‘cfv 5173 ℝcr 7734 Metcmet 12477 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 604 ax-in2 605 ax-io 699 ax-5 1427 ax-7 1428 ax-gen 1429 ax-ie1 1473 ax-ie2 1474 ax-8 1484 ax-10 1485 ax-11 1486 ax-i12 1487 ax-bndl 1489 ax-4 1490 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-13 2130 ax-14 2131 ax-ext 2139 ax-sep 4085 ax-pow 4138 ax-pr 4172 ax-un 4396 ax-setind 4499 ax-cnex 7826 ax-resscn 7827 ax-1re 7829 ax-addrcl 7832 ax-rnegex 7844 |
This theorem depends on definitions: df-bi 116 df-dc 821 df-3or 964 df-3an 965 df-tru 1338 df-fal 1341 df-nf 1441 df-sb 1743 df-eu 2009 df-mo 2010 df-clab 2144 df-cleq 2150 df-clel 2153 df-nfc 2288 df-ne 2328 df-nel 2423 df-ral 2440 df-rex 2441 df-rab 2444 df-v 2714 df-sbc 2938 df-csb 3032 df-dif 3104 df-un 3106 df-in 3108 df-ss 3115 df-if 3507 df-pw 3546 df-sn 3567 df-pr 3568 df-op 3570 df-uni 3775 df-iun 3853 df-br 3968 df-opab 4029 df-mpt 4030 df-id 4256 df-xp 4595 df-rel 4596 df-cnv 4597 df-co 4598 df-dm 4599 df-rn 4600 df-res 4601 df-ima 4602 df-iota 5138 df-fun 5175 df-fn 5176 df-f 5177 df-fv 5181 df-ov 5830 df-oprab 5831 df-mpo 5832 df-1st 6091 df-2nd 6092 df-map 6598 df-pnf 7917 df-mnf 7918 df-xr 7919 df-xadd 9687 df-xmet 12484 df-met 12485 |
This theorem is referenced by: (None) |
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