English
The ncoeff map for VertexOperator relates to the coefficient map by ncoeff(A)(n) = coeff(A)(-n-1).
Русский
Карта ncoeff для VertexOperator задаёт отношение: ncoeff(A)(n) = coeff(A)(-n-1).
LaTeX
$$$ncoeff A\; n = coeff A(-n-1)$$$
Lean4
/-- The coefficient of a vertex operator under normalized indexing. -/
def ncoeff : VertexOperator R V →ₗ[R] ℤ → Module.End R V
where
toFun A n := HVertexOperator.coeff A (-n - 1)
map_add' _ _ := by ext; simp
map_smul' _ _ := by ext; simp