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Description: Equivalence of ordered pair abstraction equality and biconditional. Version of eqopab2b with a disjoint variable condition, which does not require ax-13 . (Contributed by Mario Carneiro, 4-Jan-2017) Avoid ax-13 . (Revised by GG, 26-Jan-2024)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | eqopab2bw | |- ( { <. x , y >. | ph } = { <. x , y >. | ps } <-> A. x A. y ( ph <-> ps ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ssopab2bw | |- ( { <. x , y >. | ph } C_ { <. x , y >. | ps } <-> A. x A. y ( ph -> ps ) ) |
|
| 2 | ssopab2bw | |- ( { <. x , y >. | ps } C_ { <. x , y >. | ph } <-> A. x A. y ( ps -> ph ) ) |
|
| 3 | 1 2 | anbi12i | |- ( ( { <. x , y >. | ph } C_ { <. x , y >. | ps } /\ { <. x , y >. | ps } C_ { <. x , y >. | ph } ) <-> ( A. x A. y ( ph -> ps ) /\ A. x A. y ( ps -> ph ) ) ) |
| 4 | eqss | |- ( { <. x , y >. | ph } = { <. x , y >. | ps } <-> ( { <. x , y >. | ph } C_ { <. x , y >. | ps } /\ { <. x , y >. | ps } C_ { <. x , y >. | ph } ) ) |
|
| 5 | 2albiim | |- ( A. x A. y ( ph <-> ps ) <-> ( A. x A. y ( ph -> ps ) /\ A. x A. y ( ps -> ph ) ) ) |
|
| 6 | 3 4 5 | 3bitr4i | |- ( { <. x , y >. | ph } = { <. x , y >. | ps } <-> A. x A. y ( ph <-> ps ) ) |