Description: Equality law for relations being herditary over a class. (Contributed by RP, 27-Mar-2020)
Ref | Expression | ||
---|---|---|---|
Assertion | heeq12 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | simpl | ||
2 | simpr | ||
3 | 1 2 | imaeq12d | |
4 | 3 2 | sseq12d | |
5 | df-he | ||
6 | df-he | ||
7 | 4 5 6 | 3bitr4g |