Description: The supremum of a set of ordinals exists. (Contributed by RP, 23-Jan-2025)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | onsupex3 | |- ( ( A C_ On /\ A e. V ) -> |^| { x e. On | A. y e. A y C_ x } e. _V ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | onsupcl3 |  |-  ( ( A C_ On /\ A e. V ) -> |^| { x e. On | A. y e. A y C_ x } e. On ) | |
| 2 | 1 | elexd |  |-  ( ( A C_ On /\ A e. V ) -> |^| { x e. On | A. y e. A y C_ x } e. _V ) |