English
As before, truncation distributes over multiplication by a constant: trunc(C(a)·p) = C(a)·trunc(p).
Русский
Как и раньше, усечение распространяется на умножение константы: trunc(C(a)·p) = C(a)·trunc(p).
LaTeX
$$$$ \\operatorname{trunc} R n (C a \\cdot p) = C a \\cdot \\operatorname{trunc} R n p. $$$$
Lean4
@[simp]
theorem trunc'_C (n : σ →₀ ℕ) (a : R) : trunc' R n (C a) = MvPolynomial.C a :=
MvPolynomial.ext _ _ fun m ↦ by
classical
rw [coeff_trunc', coeff_C, MvPolynomial.coeff_C]
split_ifs with H <;>
first
| rfl
| try simp_all
exfalso; apply H; subst m; exact zero_le n