English
The coefficient after applying group action equals the original coefficient: g • (prodXSubSMul G R x).coeff n = (prodXSubSMul G R x).coeff n.
Русский
После применения действия группы коэффициент остаётся неизменным: g • (prodXSubSMul G R x).coeff n = (prodXSubSMul G R x).coeff n.
LaTeX
$$$g \cdot (prodXSubSMul\ G\ R\ x).\text{coeff } n = (prodXSubSMul\ G\ R\ x).\text{coeff } n$.$$
Lean4
theorem coeff (x : R) (g : G) (n : ℕ) : g • (prodXSubSMul G R x).coeff n = (prodXSubSMul G R x).coeff n := by
rw [← Polynomial.coeff_smul, prodXSubSMul.smul]