The Proper Basis for a Zero-dimensional Polynomial Ideal (2101.03482v2)

Abstract: The proper basis formulated herein constitutes an improvement on the Gr\"obner basis for a zero-dimensional polynomial ideal. Let $K[\mathbf{x}]$ be a polynomial ring over a field $K$ with $\mathbf{x}:=(x_1,\dotsc,x_n)$. With $x_1$ being the least variable, a zero-dimensional polynomial ideal $I\subset K[\mathbf{x}]$ always has an eliminant $\chi\in K[x_1]\setminus K$ such that $I\cap K[x_1]=(\chi)$ after eliminating the other variables $\tilde{\mathbf{x}}:=(x_2,\dotsc,x_n)$. Hence it is excessive computation for the elimination process involving the variable $x_1$ in Buchberger's algorithm for the Gr\"obner basis. It is natural to treat $K[\mathbf{x}]$ as the algebra $K[x_1][\tilde{\mathbf{x}}]$ and define a new type of basis over $K[x_1]$ for $I$ called the proper basis. The proper basis is based on a new type of polynomial division called the proper division, which improves the division mechanism in M\"oller's algorithm over $K[x_1]$ for the Gr\"obner basis. We develop a modular algorithm over a principal ideal ring with zero divisors. The convincing efficiency of the proper basis over both Buchberger's Gr\"obner basis over $K$ and M\"oller's one over $K[x_1]$ is corroborated by a series of benchmark testings with respect to the typical \textnormal{\textsc{lex}} ordering.