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Description: The element of the relations class ( df-rels ) and the relation predicate ( df-rel ) are the same when R is a set. (Contributed by Peter Mazsa, 14-Jun-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | elrels2 | ⊢ ( 𝑅 ∈ 𝑉 → ( 𝑅 ∈ Rels ↔ 𝑅 ⊆ ( V × V ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-rels | ⊢ Rels = 𝒫 ( V × V ) | |
| 2 | 1 | eleq2i | ⊢ ( 𝑅 ∈ Rels ↔ 𝑅 ∈ 𝒫 ( V × V ) ) |
| 3 | elpwg | ⊢ ( 𝑅 ∈ 𝑉 → ( 𝑅 ∈ 𝒫 ( V × V ) ↔ 𝑅 ⊆ ( V × V ) ) ) | |
| 4 | 2 3 | bitrid | ⊢ ( 𝑅 ∈ 𝑉 → ( 𝑅 ∈ Rels ↔ 𝑅 ⊆ ( V × V ) ) ) |