Description: Elementhood in the first set of an intersection - deduction version. (Contributed by Thierry Arnoux, 3-May-2020)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | elin1d.1 | |- ( ph -> X e. ( A i^i B ) ) | |
| Assertion | elin2d | |- ( ph -> X e. B ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | elin1d.1 | |- ( ph -> X e. ( A i^i B ) ) | |
| 2 | elinel2 | |- ( X e. ( A i^i B ) -> X e. B ) | |
| 3 | 1 2 | syl | |- ( ph -> X e. B ) |