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| Mirrors > Home > NFE Home > Th. List > df-0c | GIF version | ||
| Description: Define cardinal zero. (Contributed by SF, 12-Jan-2015.) |
| Ref | Expression |
|---|---|
| df-0c | ⊢ 0c = {∅} |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | c0c 4374 | . 2 class 0c | |
| 2 | c0 3550 | . . 3 class ∅ | |
| 3 | 2 | csn 3737 | . 2 class {∅} |
| 4 | 1, 3 | wceq 1642 | 1 wff 0c = {∅} |
| Colors of variables: wff setvar class |
| This definition is referenced by: 0cex 4392 0cnsuc 4401 addcid1 4405 el0c 4421 nnsucelr 4428 nndisjeq 4429 ssfin 4470 0ceven 4505 lec0cg 6198 |
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