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Mirrors > Home > NFE Home > Th. List > df-2c | Unicode version |
Description: Define cardinal two. This is the set of all sets with two unique elements. (Contributed by Scott Fenton, 24-Feb-2015.) |
Ref | Expression |
---|---|
df-2c | 2c Nc |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | c2c 6094 | . 2 2c | |
2 | c0 3550 | . . . 4 | |
3 | cvv 2859 | . . . 4 | |
4 | 2, 3 | cpr 3738 | . . 3 |
5 | 4 | cnc 6091 | . 2 Nc |
6 | 1, 5 | wceq 1642 | 1 2c Nc |
Colors of variables: wff setvar class |
This definition is referenced by: 1p1e2c 6155 2p1e3c 6156 nncdiv3lem2 6276 |
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