record concrete_space : Type ≝
{ bp:> BP;
- downarrow: form bp → oa_P (form bp);
+ downarrow: unary_morphism (oa_P (form bp)) (oa_P (form bp));
downarrow_is_sat: is_saturation ? downarrow;
- converges: ∀q1,q2:form bp.
+ converges: ∀q1,q2.
or_f_minus ?? (⊩) q1 ∧ or_f_minus ?? (⊩) q2 =
or_f_minus ?? (⊩) ((downarrow q1) ∧ (downarrow q2));
all_covered: (*⨍^-_bp*) or_f_minus ?? (⊩) (oa_one (form bp)) = oa_one (concr bp);