English
The constructed sequence sMk associated with x : F (M F) yields, at every step, an AllAgree property: AllAgree (Approx.sMk x).
Русский
Пусть x : F (M F). Тогда последовательность sMk образующаяся обеспечивает на каждом шаге свойство AllAgree: AllAgree(Approx.sMk x).
LaTeX
$$$\\operatorname{PFunctor.M.Approx.P_mk}\\ (x:\\, F.(M.F))\\;:\\; \\operatorname{AllAgree}(\\operatorname{Approx.sMk} x)$$$
Lean4
/-- generates the approximations needed for `M.mk` -/
protected def sMk (x : F (M F)) : ∀ n, CofixA F n
| 0 => CofixA.continue
| succ n => CofixA.intro x.1 fun i => (x.2 i).approx n