fact: Definition oppℝ_Req_involutive := λ"Cx" Eeq_implies_Req @ (oppℝ_Cauchy @ (oppℝ_Cauchy @ "Cx")) @ oppℝ_Eeq_involutive.
imports: QArith Psatz ClassicalRealizability.Kbase ClassicalRealizability.Rationals ClassicalRealizability.Real_definitions ClassicalRealizability.Real_relations