Description: Another quantifier-free definition of On . (Contributed by Scott Fenton, 4-May-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | dfon4 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfon3 | |
|
2 | df-ima | |
|
3 | df-res | |
|
4 | indif1 | |
|
5 | 3 4 | eqtri | |
6 | 5 | rneqi | |
7 | 2 6 | eqtri | |
8 | 7 | difeq2i | |
9 | 1 8 | eqtr4i | |