7.2.1 ideal (plural)
For PLURAL ideals are left ideals, unless stated otherwise.
Ideals are represented as lists of polynomials which are interpreted as
left generators of the ideal.
For the operations with two-sided ideals see twostd (plural).
Like polynomials, ideals can only be defined or accessed with respect to a basering.
size counts only the non-zero generators of an ideal
ncols counts all generators.