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Description: Membership in an intersection implies membership in the first set. (Contributed by Glauco Siliprandi, 11-Dec-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | elinel1 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | elin | ||
| 2 | 1 | simplbi |