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Mirrors > Home > ILE Home > Th. List > 0elon | GIF version |
Description: The empty set is an ordinal number. Corollary 7N(b) of [Enderton] p. 193. (Contributed by NM, 17-Sep-1993.) |
Ref | Expression |
---|---|
0elon | ⊢ ∅ ∈ On |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ord0 4313 | . 2 ⊢ Ord ∅ | |
2 | 0ex 4055 | . . 3 ⊢ ∅ ∈ V | |
3 | 2 | elon 4296 | . 2 ⊢ (∅ ∈ On ↔ Ord ∅) |
4 | 1, 3 | mpbir 145 | 1 ⊢ ∅ ∈ On |
Colors of variables: wff set class |
Syntax hints: ∈ wcel 1480 ∅c0 3363 Ord word 4284 Oncon0 4285 |
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 603 ax-in2 604 ax-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2121 ax-nul 4054 |
This theorem depends on definitions: df-bi 116 df-tru 1334 df-nf 1437 df-sb 1736 df-clab 2126 df-cleq 2132 df-clel 2135 df-nfc 2270 df-ral 2421 df-rex 2422 df-v 2688 df-dif 3073 df-in 3077 df-ss 3084 df-nul 3364 df-pw 3512 df-uni 3737 df-tr 4027 df-iord 4288 df-on 4290 |
This theorem is referenced by: inton 4315 onn0 4322 onm 4323 limon 4429 ordtriexmid 4437 ordtri2orexmid 4438 onsucsssucexmid 4442 onsucelsucexmid 4445 ordsoexmid 4477 ordpwsucexmid 4485 ordtri2or2exmid 4486 tfr0dm 6219 1on 6320 ordgt0ge1 6332 omv 6351 oa0 6353 om0 6354 oei0 6355 omcl 6357 omv2 6361 oaword1 6367 nna0r 6374 nnm0r 6375 card0 7044 |
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