Description: The composition of two sets is a set. (Contributed by SN, 7-Feb-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | coexd.1 | |- ( ph -> A e. V ) |
|
| coexd.2 | |- ( ph -> B e. W ) |
||
| Assertion | coexd | |- ( ph -> ( A o. B ) e. _V ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | coexd.1 | |- ( ph -> A e. V ) |
|
| 2 | coexd.2 | |- ( ph -> B e. W ) |
|
| 3 | coexg | |- ( ( A e. V /\ B e. W ) -> ( A o. B ) e. _V ) |
|
| 4 | 1 2 3 | syl2anc | |- ( ph -> ( A o. B ) e. _V ) |