-notation "□ \sub b" non associative with precedence 90 for @{'box $b}.
-notation > "□_term 90 b" non associative with precedence 90 for @{'box $b}.
-interpretation "Universal image ⊩⎻*" 'box x = (fun12 _ _ (or_f_minus_star _ _) (rel x)).
-
-notation "◊ \sub b" non associative with precedence 90 for @{'diamond $b}.
-notation > "◊_term 90 b" non associative with precedence 90 for @{'diamond $b}.
-interpretation "Existential image ⊩" 'diamond x = (fun12 _ _ (or_f _ _) (rel x)).
-
-notation "'Rest' \sub b" non associative with precedence 90 for @{'rest $b}.
-notation > "'Rest'⎽term 90 b" non associative with precedence 90 for @{'rest $b}.
-interpretation "Universal pre-image ⊩*" 'rest x = (fun12 _ _ (or_f_star _ _) (rel x)).
-
-notation "'Ext' \sub b" non associative with precedence 90 for @{'ext $b}.
-notation > "'Ext'⎽term 90 b" non associative with precedence 90 for @{'ext $b}.
-interpretation "Existential pre-image ⊩⎻" 'ext x = (fun12 _ _ (or_f_minus _ _) (rel x)).
-
-definition A : ∀b:BP. unary_morphism1 (form b) (form b).