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Description: The range of the membership relation is the universal class minus the empty set. (Contributed by BJ, 26-Dec-2023)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | rnep |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | dfrn2 | ||
| 2 | nfab1 | ||
| 3 | nfcv | ||
| 4 | abid | ||
| 5 | epel | ||
| 6 | 5 | exbii | |
| 7 | neq0 | ||
| 8 | 7 | bicomi | |
| 9 | velsn | ||
| 10 | 9 | bicomi | |
| 11 | 10 | notbii | |
| 12 | 6 8 11 | 3bitri | |
| 13 | velcomp | ||
| 14 | 13 | bicomi | |
| 15 | 4 12 14 | 3bitri | |
| 16 | 2 3 15 | eqri | |
| 17 | 1 16 | eqtri |