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Description: The law of concretion for a binary relation. Ordered pair membership in an ordered pair class abstraction. (Contributed by Mario Carneiro, 28-Apr-2015)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | brab2a.1 | ||
| brab2a.2 | |||
| Assertion | brab2a |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | brab2a.1 | ||
| 2 | brab2a.2 | ||
| 3 | opabssxp | ||
| 4 | 2 3 | eqsstri | |
| 5 | 4 | brel | |
| 6 | df-br | ||
| 7 | 2 | eleq2i | |
| 8 | 6 7 | bitri | |
| 9 | 1 | opelopab2a | |
| 10 | 8 9 | bitrid | |
| 11 | 5 10 | biadanii |