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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 | ⊢ [⊊] = { 〈 𝑥 , 𝑦 〉 ∣ 𝑥 ⊊ 𝑦 } |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | crpss | ⊢ [⊊] | |
| 1 | vx | ⊢ 𝑥 | |
| 2 | vy | ⊢ 𝑦 | |
| 3 | 1 | cv | ⊢ 𝑥 |
| 4 | 2 | cv | ⊢ 𝑦 |
| 5 | 3 4 | wpss | ⊢ 𝑥 ⊊ 𝑦 |
| 6 | 5 1 2 | copab | ⊢ { 〈 𝑥 , 𝑦 〉 ∣ 𝑥 ⊊ 𝑦 } |
| 7 | 0 6 | wceq | ⊢ [⊊] = { 〈 𝑥 , 𝑦 〉 ∣ 𝑥 ⊊ 𝑦 } |