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| Mirrors > Home > NFE Home > Th. List > df-nc | Unicode version | ||
| Description: Define the cardinality operation. This is the unique cardinal number containing a given set. Definition from [Rosser] p. 371. (Contributed by Scott Fenton, 24-Feb-2015.) |
| Ref | Expression |
|---|---|
| df-nc |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | cA |
. . 3
| |
| 2 | 1 | cnc 6091 |
. 2
|
| 3 | cen 6028 |
. . 3
| |
| 4 | 1, 3 | cec 5945 |
. 2
|
| 5 | 2, 4 | wceq 1642 |
1
|
| Colors of variables: wff setvar class |
| This definition is referenced by: nceq 6108 ncex 6117 elncs 6119 ncidg 6122 ncprc 6124 elnc 6125 eqncg 6126 ncseqnc 6128 mucnc 6131 df0c2 6137 1cnc 6139 ncdisjeq 6148 |
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