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Description: Property of epsilon relation, see also extid , extssr and the comment of df-ssr . (Contributed by Peter Mazsa, 10-Jul-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | extep |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | eccnvep | ||
| 2 | eccnvep | ||
| 3 | 1 2 | eqeqan12d |