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| Description: Define the class of all cardinal numbers. The notation "Card" is used in Exercise 5(G) of [JustWeese] p. 174. It should not be confused with the lower-case "card" for the cardinal number function df-card 3623. |
| Ref | Expression |
|---|---|
| df-cardn |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ccdn 3711 |
. 2
| |
| 2 | com 2372 |
. . 3
| |
| 3 | cale 3621 |
. . . 4
| |
| 4 | 3 | crn 2411 |
. . 3
|
| 5 | 2, 4 | cun 1485 |
. 2
|
| 6 | 1, 5 | wceq 1091 |
1
|
| Colors of variables: wff set class |
| This definition is referenced by: elcard 3713 |