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Mirrors > Home > ILE Home > Th. List > 0elon | Unicode 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 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ord0 4146 | . 2 | |
2 | 0ex 3905 | . . 3 | |
3 | 2 | elon 4129 | . 2 |
4 | 1, 3 | mpbir 144 | 1 |
Colors of variables: wff set class |
Syntax hints: wcel 1433 c0 3251 word 4117 con0 4118 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-in1 576 ax-in2 577 ax-io 662 ax-5 1376 ax-7 1377 ax-gen 1378 ax-ie1 1422 ax-ie2 1423 ax-8 1435 ax-10 1436 ax-11 1437 ax-i12 1438 ax-bndl 1439 ax-4 1440 ax-17 1459 ax-i9 1463 ax-ial 1467 ax-i5r 1468 ax-ext 2063 ax-nul 3904 |
This theorem depends on definitions: df-bi 115 df-tru 1287 df-nf 1390 df-sb 1686 df-clab 2068 df-cleq 2074 df-clel 2077 df-nfc 2208 df-ral 2353 df-rex 2354 df-v 2603 df-dif 2975 df-in 2979 df-ss 2986 df-nul 3252 df-pw 3384 df-uni 3602 df-tr 3876 df-iord 4121 df-on 4123 |
This theorem is referenced by: inton 4148 onn0 4155 onm 4156 limon 4257 ordtriexmid 4265 ordtri2orexmid 4266 onsucsssucexmid 4270 onsucelsucexmid 4273 ordsoexmid 4305 ordpwsucexmid 4313 ordtri2or2exmid 4314 tfr0 5960 1on 6031 ordgt0ge1 6041 omv 6058 oa0 6060 om0 6061 oei0 6062 omcl 6064 omv2 6068 oaword1 6073 nna0r 6080 nnm0r 6081 card0 6457 |
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