Description: If a class is a member of another class, then it is a set. Deduction associated with elex . (Contributed by Glauco Siliprandi, 11-Oct-2020)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | elexd.1 | ||
| Assertion | elexd |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | elexd.1 | ||
| 2 | elex | ||
| 3 | 1 2 | syl |