Description: A set is an element of the domain of a ordered pair class abstraction iff there is a second set so that both sets fulfil the wff of the class abstraction. (Contributed by AV, 19-Oct-2023)
Ref | Expression | ||
---|---|---|---|
Hypothesis | dmopabel.d | ||
Assertion | dmopabelb |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dmopabel.d | ||
2 | dmopab | ||
3 | 2 | eleq2i | |
4 | 1 | exbidv | |
5 | eqid | ||
6 | 4 5 | elab2g | |
7 | 3 6 | syl5bb |