English
The action of a scalar triple (R,S,End(A)) forms a scalar tower, i.e., compatibility of the two-step action on End(A).
Русский
Действия скаляров образуют скалярную башню на End(A): совместимость двухступенчатого действия на End(A).
LaTeX
$$$ [IsScalarTower\ R\ S\ (\mathrm{End}(A))]$$$
Lean4
@[ext (iff := false)]
theorem ext {a b : ExtensionOf i f} (domain_eq : a.domain = b.domain)
(to_fun_eq : ∀ ⦃x : N⦄ ⦃ha : x ∈ a.domain⦄ ⦃hb : x ∈ b.domain⦄, a.toLinearPMap ⟨x, ha⟩ = b.toLinearPMap ⟨x, hb⟩) :
a = b := by
rcases a with ⟨a, a_le, e1⟩
congr
exact LinearPMap.ext domain_eq to_fun_eq