Description: Refinement is a relation. (Contributed by Jeff Hankins, 18-Jan-2010) (Revised by Thierry Arnoux, 3-Feb-2020)
Ref | Expression | ||
---|---|---|---|
Assertion | refrel | ⊢ Rel Ref |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-ref | ⊢ Ref = { 〈 𝑥 , 𝑦 〉 ∣ ( ∪ 𝑦 = ∪ 𝑥 ∧ ∀ 𝑧 ∈ 𝑥 ∃ 𝑤 ∈ 𝑦 𝑧 ⊆ 𝑤 ) } | |
2 | 1 | relopabiv | ⊢ Rel Ref |