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Description: Two classes that are related by a binary relation are sets. Inference form. (Contributed by BJ, 3-Oct-2022)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | brrelexi.1 | ||
| Assertion | brrelex12i |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | brrelexi.1 | ||
| 2 | brrelex12 | ||
| 3 | 1 2 | mpan |