explicit(WittPolynomialRing) -- Expresses a WittPolynomialRing as a finitely generated algebra over the integers.

If R = (ZZ/p)[x_1,..., x_d] is a polynomial ring over a prime field ZZ/p, and $n \geq 1$ is an integer, then $W_n(R)$ can be identified with a certain $\mathbb{Z} / p^n$ subalgebra of a polynomial ring in d variables over $\mathbb{Z} / p^n$. This method finds the relations between these generators in order to express $W_n(R)$ as a finitely generated ZZ-algebra. Note that the number of generators and relations grows very fast with p and d.

When the method is applied when R is a polynomial ring over a finite but not prime field, the package essentially treats R as a quotient of a polynomial ring over its prime subfield.