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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 4308 | . 2 ⊢ Ord ∅ | |
2 | 0ex 4050 | . . 3 ⊢ ∅ ∈ V | |
3 | 2 | elon 4291 | . 2 ⊢ (∅ ∈ On ↔ Ord ∅) |
4 | 1, 3 | mpbir 145 | 1 ⊢ ∅ ∈ On |
Colors of variables: wff set class |
Syntax hints: ∈ wcel 1480 ∅c0 3358 Ord word 4279 Oncon0 4280 |
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 2119 ax-nul 4049 |
This theorem depends on definitions: df-bi 116 df-tru 1334 df-nf 1437 df-sb 1736 df-clab 2124 df-cleq 2130 df-clel 2133 df-nfc 2268 df-ral 2419 df-rex 2420 df-v 2683 df-dif 3068 df-in 3072 df-ss 3079 df-nul 3359 df-pw 3507 df-uni 3732 df-tr 4022 df-iord 4283 df-on 4285 |
This theorem is referenced by: inton 4310 onn0 4317 onm 4318 limon 4424 ordtriexmid 4432 ordtri2orexmid 4433 onsucsssucexmid 4437 onsucelsucexmid 4440 ordsoexmid 4472 ordpwsucexmid 4480 ordtri2or2exmid 4481 tfr0dm 6212 1on 6313 ordgt0ge1 6325 omv 6344 oa0 6346 om0 6347 oei0 6348 omcl 6350 omv2 6354 oaword1 6360 nna0r 6367 nnm0r 6368 card0 7037 |
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