Description: A set equinumerous to ordinal 3 is a triple. (Contributed by Mario Carneiro, 5-Jan-2016)
Ref | Expression | ||
---|---|---|---|
Assertion | en3 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 2on | ||
2 | 1 | onordi | |
3 | df-3o | ||
4 | en2 | ||
5 | tpass | ||
6 | 5 | enp1ilem | |
7 | 6 | 2eximdv | |
8 | 2 3 4 7 | enp1i |