Description: Reverse closure for a subring predicate. (Contributed by AV, 14-Feb-2025)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | subrngrcl | |- ( A e. ( SubRng ` R ) -> R e. Rng ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | eqid | |- ( Base ` R ) = ( Base ` R ) | |
| 2 | 1 | issubrng | |- ( A e. ( SubRng ` R ) <-> ( R e. Rng /\ ( R |`s A ) e. Rng /\ A C_ ( Base ` R ) ) ) | 
| 3 | 2 | simp1bi | |- ( A e. ( SubRng ` R ) -> R e. Rng ) |