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Mirrors > Home > ILE Home > Th. List > nnal | Unicode version |
Description: The double negation of a universal quantification implies the universal quantification of the double negation. (Contributed by BJ, 24-Nov-2023.) |
Ref | Expression |
---|---|
nnal |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | exnalim 1634 | . . 3 | |
2 | 1 | con3i 622 | . 2 |
3 | alnex 1487 | . 2 | |
4 | 2, 3 | sylibr 133 | 1 |
Colors of variables: wff set class |
Syntax hints: wn 3 wi 4 wal 1341 wex 1480 |
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 604 ax-in2 605 ax-5 1435 ax-gen 1437 ax-ie1 1481 ax-ie2 1482 ax-4 1498 ax-17 1514 ax-ial 1522 |
This theorem depends on definitions: df-bi 116 df-tru 1346 df-fal 1349 df-nf 1449 |
This theorem is referenced by: bj-stal 13630 |
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