Efficient Gröbner Bases Computation over Principal Ideal Rings

Abstract

In this paper we present a new efficient variant to compute strong Gröbner basis over quotients of principal ideal domains. We show an easy lifting process which allows us to reduce one computation over the quotient $R/nR$ to two computations over $R/aR$ and $R/bR$ where $n=ab$ with coprime $a,b$. Possibly using available factorization algorithms we may thus recursively reduce some strong Gröbner basis computations to Gröbner basis computations over fields for prime factors of $n$, at least for squarefree $n$. Considering now a computation over $R/nR$ we can run a standard Gröbner basis algorithm pretending $R/nR$ to be field. If we discover a non-invertible leading coefficient $c$, we use this information to try to split $n=ab$ with coprime $a,b$. If no such $c$ is discovered, the returned Gröbner basis is already a strong Gröbner basis for the input ideal over $R/nR$.