English
init_n is compatible with natural scalar multiplication: init_n(m • x) = m • init_n(x).
Русский
init_n совместимо с натуральным скаляром: init_n(m · x) = m · init_n(x).
LaTeX
$$$$\operatorname{init}_n(m \cdot x) = m \cdot \operatorname{init}_n x.$$$$
Lean4
/-- The composition of polynomial functions is polynomial. -/
instance comp {g f} [hg : IsPoly p g] [hf : IsPoly p f] : IsPoly p fun R _Rcr => @g R _Rcr ∘ @f R _Rcr :=
by
obtain ⟨φ, hf⟩ := hf
obtain ⟨ψ, hg⟩ := hg
use fun n => bind₁ φ (ψ n)
intros
simp only [aeval_bind₁, Function.comp, hg, hf]