fact: Definition restriction_relation (R:relation T) (S:Ensemble T) : relation ({z:T | In S z}) := fun (x y:{z:T | In S z}) => R (proj1_sig x) (proj1_sig y).
imports: Relation_Definitions Relation_Definitions_Implicit Classical_Wf Description FunctionalExtensionality Classical ZornsLemma ProofIrrelevance EnsemblesSpec