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Mirrors > Home > MPE Home > Th. List > Mathboxes > ordtop | Structured version Visualization version GIF version |
Description: An ordinal is a topology iff it is not its supremum (union), proven without the Axiom of Regularity. (Contributed by Chen-Pang He, 1-Nov-2015.) |
Ref | Expression |
---|---|
ordtop | ⊢ (Ord 𝐽 → (𝐽 ∈ Top ↔ 𝐽 ≠ ∪ 𝐽)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqid 2798 | . . . 4 ⊢ ∪ 𝐽 = ∪ 𝐽 | |
2 | 1 | topopn 21511 | . . 3 ⊢ (𝐽 ∈ Top → ∪ 𝐽 ∈ 𝐽) |
3 | nordeq 6178 | . . . 4 ⊢ ((Ord 𝐽 ∧ ∪ 𝐽 ∈ 𝐽) → 𝐽 ≠ ∪ 𝐽) | |
4 | 3 | ex 416 | . . 3 ⊢ (Ord 𝐽 → (∪ 𝐽 ∈ 𝐽 → 𝐽 ≠ ∪ 𝐽)) |
5 | 2, 4 | syl5 34 | . 2 ⊢ (Ord 𝐽 → (𝐽 ∈ Top → 𝐽 ≠ ∪ 𝐽)) |
6 | onsuctop 33894 | . . 3 ⊢ (∪ 𝐽 ∈ On → suc ∪ 𝐽 ∈ Top) | |
7 | 6 | ordtoplem 33896 | . 2 ⊢ (Ord 𝐽 → (𝐽 ≠ ∪ 𝐽 → 𝐽 ∈ Top)) |
8 | 5, 7 | impbid 215 | 1 ⊢ (Ord 𝐽 → (𝐽 ∈ Top ↔ 𝐽 ≠ ∪ 𝐽)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 209 ∈ wcel 2111 ≠ wne 2987 ∪ cuni 4800 Ord word 6158 Topctop 21498 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2113 ax-9 2121 ax-10 2142 ax-11 2158 ax-12 2175 ax-ext 2770 ax-sep 5167 ax-nul 5174 ax-pow 5231 ax-pr 5295 ax-un 7441 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 845 df-3or 1085 df-3an 1086 df-tru 1541 df-ex 1782 df-nf 1786 df-sb 2070 df-mo 2598 df-eu 2629 df-clab 2777 df-cleq 2791 df-clel 2870 df-nfc 2938 df-ne 2988 df-ral 3111 df-rex 3112 df-rab 3115 df-v 3443 df-sbc 3721 df-dif 3884 df-un 3886 df-in 3888 df-ss 3898 df-pss 3900 df-nul 4244 df-if 4426 df-pw 4499 df-sn 4526 df-pr 4528 df-tp 4530 df-op 4532 df-uni 4801 df-br 5031 df-opab 5093 df-mpt 5111 df-tr 5137 df-id 5425 df-eprel 5430 df-po 5438 df-so 5439 df-fr 5478 df-we 5480 df-xp 5525 df-rel 5526 df-cnv 5527 df-co 5528 df-dm 5529 df-ord 6162 df-on 6163 df-suc 6165 df-iota 6283 df-fun 6326 df-fv 6332 df-topgen 16709 df-top 21499 df-bases 21551 |
This theorem is referenced by: ordtopconn 33900 ordtopt0 33903 ordcmp 33908 |
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