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Mirrors > Home > ILE Home > Th. List > df-sn | Unicode version |
Description: Define the singleton of a class. Definition 7.1 of [Quine] p. 48. For convenience, it is well-defined for proper classes, i.e., those that are not elements of , although it is not very meaningful in this case. For an alternate definition see dfsn2 3541. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
df-sn |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cA | . . 3 | |
2 | 1 | csn 3527 | . 2 |
3 | vx | . . . . 5 | |
4 | 3 | cv 1330 | . . . 4 |
5 | 4, 1 | wceq 1331 | . . 3 |
6 | 5, 3 | cab 2125 | . 2 |
7 | 2, 6 | wceq 1331 | 1 |
Colors of variables: wff set class |
This definition is referenced by: sneq 3538 elsng 3542 csbsng 3584 rabsn 3590 pw0 3667 iunid 3868 dfiota2 5089 uniabio 5098 dfimafn2 5471 fnsnfv 5480 snec 6490 bdcsn 13068 |
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