Description: Restricted subset binary relation. (Contributed by Peter Mazsa, 25-Nov-2019)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | brssrres | |- ( C e. V -> ( B ( _S |` A ) C <-> ( B e. A /\ B C_ C ) ) )  | 
				
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | brres | |- ( C e. V -> ( B ( _S |` A ) C <-> ( B e. A /\ B _S C ) ) )  | 
						|
| 2 | brssr | |- ( C e. V -> ( B _S C <-> B C_ C ) )  | 
						|
| 3 | 2 | anbi2d | |- ( C e. V -> ( ( B e. A /\ B _S C ) <-> ( B e. A /\ B C_ C ) ) )  | 
						
| 4 | 1 3 | bitrd | |- ( C e. V -> ( B ( _S |` A ) C <-> ( B e. A /\ B C_ C ) ) )  |