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Mirrors > Home > ILE Home > Th. List > uni0 | Unicode version |
Description: The union of the empty set is the empty set. Theorem 8.7 of [Quine] p. 54. (Reproved without relying on ax-nul by Eric Schmidt.) (Contributed by NM, 16-Sep-1993.) (Revised by Eric Schmidt, 4-Apr-2007.) |
Ref | Expression |
---|---|
uni0 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ss 3401 | . 2 | |
2 | uni0b 3761 | . 2 | |
3 | 1, 2 | mpbir 145 | 1 |
Colors of variables: wff set class |
Syntax hints: wceq 1331 wss 3071 c0 3363 csn 3527 cuni 3736 |
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 |
This theorem depends on definitions: df-bi 116 df-tru 1334 df-fal 1337 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-sn 3533 df-uni 3737 |
This theorem is referenced by: iununir 3896 nnpredcl 4536 unixp0im 5075 iotanul 5103 1st0 6042 2nd0 6043 brtpos0 6149 tpostpos 6161 nnsucuniel 6391 sup00 6890 0opn 12173 |
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