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Mirrors > Home > ILE Home > Th. List > ord0 | Unicode version |
Description: The empty set is an ordinal class. (Contributed by NM, 11-May-1994.) |
Ref | Expression |
---|---|
ord0 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | tr0 3886 | . 2 | |
2 | ral0 3342 | . 2 | |
3 | dford3 4122 | . 2 | |
4 | 1, 2, 3 | mpbir2an 883 | 1 |
Colors of variables: wff set class |
Syntax hints: wral 2348 c0 3251 wtr 3875 word 4117 |
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 |
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-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 |
This theorem is referenced by: 0elon 4147 ordtriexmidlem 4263 2ordpr 4267 smo0 5936 |
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