English
If o is a successor-limit ordinal, then the derivative at o is the supremum of the derivatives at all b with b < o: derivFamily f o = ⨆ b : Set.Iio o, derivFamily f b.
Русский
Если o является предельным по отношению к succ, то производная в o равна верхней границе всех значений derivFamily f b, где b < o: derivFamily f o = ⨆ b : Set.Iio o, derivFamily f b.
LaTeX
$$$$ IsSuccLimit(o) \rightarrow derivFamily f o = \bigvee_{b \in \mathrm{Iio}(o)} derivFamily f b. $$$$
Lean4
theorem derivFamily_limit (f : ι → Ordinal → Ordinal) {o} :
IsSuccLimit o → derivFamily f o = ⨆ b : Set.Iio o, derivFamily f b :=
limitRecOn_limit _ _ _ _