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Mirrors > Home > ILE Home > Th. List > dfnul2 | Unicode version |
Description: Alternate definition of the empty set. Definition 5.14 of [TakeutiZaring] p. 20. (Contributed by NM, 26-Dec-1996.) |
Ref | Expression |
---|---|
dfnul2 |
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Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-nul 3438 |
. . . 4
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2 | 1 | eleq2i 2256 |
. . 3
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3 | eldif 3153 |
. . 3
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4 | pm3.24 694 |
. . . 4
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5 | eqid 2189 |
. . . . 5
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6 | 5 | notnoti 646 |
. . . 4
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7 | 4, 6 | 2false 702 |
. . 3
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8 | 2, 3, 7 | 3bitri 206 |
. 2
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9 | 8 | abbi2i 2304 |
1
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Colors of variables: wff set class |
Syntax hints: ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 615 ax-in2 616 ax-io 710 ax-5 1458 ax-7 1459 ax-gen 1460 ax-ie1 1504 ax-ie2 1505 ax-8 1515 ax-10 1516 ax-11 1517 ax-i12 1518 ax-bndl 1520 ax-4 1521 ax-17 1537 ax-i9 1541 ax-ial 1545 ax-i5r 1546 ax-ext 2171 |
This theorem depends on definitions: df-bi 117 df-tru 1367 df-nf 1472 df-sb 1774 df-clab 2176 df-cleq 2182 df-clel 2185 df-nfc 2321 df-v 2754 df-dif 3146 df-nul 3438 |
This theorem is referenced by: dfnul3 3440 rab0 3466 iotanul 5211 |
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