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Mirrors > Home > ILE Home > Th. List > bastop | GIF version |
Description: Two ways to express that a basis is a topology. (Contributed by NM, 18-Jul-2006.) |
Ref | Expression |
---|---|
bastop | ⊢ (𝐵 ∈ TopBases → (𝐵 ∈ Top ↔ (topGen‘𝐵) = 𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | tgtop 12615 | . 2 ⊢ (𝐵 ∈ Top → (topGen‘𝐵) = 𝐵) | |
2 | tgcl 12611 | . . 3 ⊢ (𝐵 ∈ TopBases → (topGen‘𝐵) ∈ Top) | |
3 | eleq1 2227 | . . 3 ⊢ ((topGen‘𝐵) = 𝐵 → ((topGen‘𝐵) ∈ Top ↔ 𝐵 ∈ Top)) | |
4 | 2, 3 | syl5ibcom 154 | . 2 ⊢ (𝐵 ∈ TopBases → ((topGen‘𝐵) = 𝐵 → 𝐵 ∈ Top)) |
5 | 1, 4 | impbid2 142 | 1 ⊢ (𝐵 ∈ TopBases → (𝐵 ∈ Top ↔ (topGen‘𝐵) = 𝐵)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ↔ wb 104 = wceq 1342 ∈ wcel 2135 ‘cfv 5182 topGenctg 12513 Topctop 12542 TopBasesctb 12587 |
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-io 699 ax-5 1434 ax-7 1435 ax-gen 1436 ax-ie1 1480 ax-ie2 1481 ax-8 1491 ax-10 1492 ax-11 1493 ax-i12 1494 ax-bndl 1496 ax-4 1497 ax-17 1513 ax-i9 1517 ax-ial 1521 ax-i5r 1522 ax-13 2137 ax-14 2138 ax-ext 2146 ax-sep 4094 ax-pow 4147 ax-pr 4181 ax-un 4405 |
This theorem depends on definitions: df-bi 116 df-3an 969 df-tru 1345 df-nf 1448 df-sb 1750 df-eu 2016 df-mo 2017 df-clab 2151 df-cleq 2157 df-clel 2160 df-nfc 2295 df-ral 2447 df-rex 2448 df-v 2723 df-sbc 2947 df-un 3115 df-in 3117 df-ss 3124 df-pw 3555 df-sn 3576 df-pr 3577 df-op 3579 df-uni 3784 df-br 3977 df-opab 4038 df-mpt 4039 df-id 4265 df-xp 4604 df-rel 4605 df-cnv 4606 df-co 4607 df-dm 4608 df-iota 5147 df-fun 5184 df-fv 5190 df-topgen 12519 df-top 12543 df-bases 12588 |
This theorem is referenced by: (None) |
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