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Description: Define a relation which corresponds to proper subsethood df-pss on sets. This allows to use proper subsethood with general concepts that require relations, such as strict ordering, see sorpss . (Contributed by Stefan O'Rear, 2-Nov-2014)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-rpss |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | crpss | ||
| 1 | vx | ||
| 2 | vy | ||
| 3 | 1 | cv | |
| 4 | 2 | cv | |
| 5 | 3 4 | wpss | |
| 6 | 5 1 2 | copab | |
| 7 | 0 6 | wceq |