Description: Size of a finite ordinal. (Contributed by Mario Carneiro, 5-Jan-2016)
Ref | Expression | ||
---|---|---|---|
Assertion | hash4 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 3onn | |
|
2 | df-4o | |
|
3 | hash3 | |
|
4 | 3p1e4 | |
|
5 | 1 2 3 4 | hashp1i | |