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Mirrors > Home > ILE Home > Th. List > uni0b | Unicode version |
Description: The union of a set is empty iff the set is included in the singleton of the empty set. (Contributed by NM, 12-Sep-2004.) |
Ref | Expression |
---|---|
uni0b |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eq0 3239 | . . . 4 | |
2 | 1 | ralbii 2330 | . . 3 |
3 | ralcom4 2576 | . . 3 | |
4 | 2, 3 | bitri 173 | . 2 |
5 | dfss3 2935 | . . 3 | |
6 | velsn 3392 | . . . 4 | |
7 | 6 | ralbii 2330 | . . 3 |
8 | 5, 7 | bitri 173 | . 2 |
9 | eluni2 3584 | . . . . 5 | |
10 | 9 | notbii 594 | . . . 4 |
11 | 10 | albii 1359 | . . 3 |
12 | eq0 3239 | . . 3 | |
13 | ralnex 2316 | . . . 4 | |
14 | 13 | albii 1359 | . . 3 |
15 | 11, 12, 14 | 3bitr4i 201 | . 2 |
16 | 4, 8, 15 | 3bitr4ri 202 | 1 |
Colors of variables: wff set class |
Syntax hints: wn 3 wb 98 wal 1241 wceq 1243 wcel 1393 wral 2306 wrex 2307 wss 2917 c0 3224 csn 3375 cuni 3580 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-in1 544 ax-in2 545 ax-io 630 ax-5 1336 ax-7 1337 ax-gen 1338 ax-ie1 1382 ax-ie2 1383 ax-8 1395 ax-10 1396 ax-11 1397 ax-i12 1398 ax-bndl 1399 ax-4 1400 ax-17 1419 ax-i9 1423 ax-ial 1427 ax-i5r 1428 ax-ext 2022 |
This theorem depends on definitions: df-bi 110 df-tru 1246 df-fal 1249 df-nf 1350 df-sb 1646 df-clab 2027 df-cleq 2033 df-clel 2036 df-nfc 2167 df-ral 2311 df-rex 2312 df-v 2559 df-dif 2920 df-in 2924 df-ss 2931 df-nul 3225 df-sn 3381 df-uni 3581 |
This theorem is referenced by: uni0c 3606 uni0 3607 |
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