Description: The restriction of a class to a class is included in the Cartesian product of the restricting class with the universal class. (Contributed by BJ, 16-Oct-2026)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bj-resss2 | |- ( R |` A ) C_ ( A X. _V ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-res | |- ( R |` A ) = ( R i^i ( A X. _V ) ) |
|
| 2 | inss2 | |- ( R i^i ( A X. _V ) ) C_ ( A X. _V ) |
|
| 3 | 1 2 | eqsstri | |- ( R |` A ) C_ ( A X. _V ) |