fact: Definition all_der_bound (f: fterm) (b: fterm2):= forall x i, ordinalp x -> ordinalp i -> [/\ inc x (b x i), inc i (b x i), (exists2 C, infinite_c C & b x i = cnext C) & forall t, inc t (b x i) -> inc (f t) (b x i)].
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)