arXiv subjects

Catherine St-Pierre

Publications and source records attributed to Catherine St-Pierre.

4 recordsLinked to original sources

arXiv2023

$p$-adic algorithm for bivariate Gröbner bases

We present a $p$-adic algorithm to recover the lexicographic Gröbner basis $\mathcal G$ of an ideal in $\mathbb Q[x,y]$ with a generating set in $\mathbb Z[x,y]$, with a complexity that is less than cubic in terms of the dimension of $\mathbb Q[x,y]/\langle \mathcal G \rangle$ and softly linear in the height of its coefficients. We observe that previous results of Lazard's that use Hermite normal forms to compute Gröbner bases for ideals with two generators can be generalized to a set of $t\in \mathbb N^+$ generators. We use this result to obtain a bound on the height of the coefficients of $\mathcal G$, and to control the probability of choosing a \textit{good} prime $p$ to build the $p$-adic expansion of $\mathcal G$.

math.AC↗

arXiv2023

Newton iteration for lexicographic Gröbner bases in two variables

We present an $m$-adic Newton iteration with quadratic convergence for lexicographic Gröbner basis of zero dimensional ideals in two variables. We rely on a structural result about the syzygies in such a basis due to Conca and Valla, that allowed them to explicitly describe these Gröbner bases by affine parameters; our Newton iteration works directly with these parameters.

math.AC↗

arXiv2019

Change of basis for m-primary ideals in one and two variables

Following recent work by van der Hoeven and Lecerf (ISSAC 2017), we discuss the complexity of linear mappings, called untangling and tangling by those authors, that arise in the context of computations with univariate polynomials. We give a slightly faster tangling algorithm and discuss new applications of these techniques. We show how to extend these ideas to bivariate settings, and use them to give bounds on the arithmetic complexity of certain algebras.

cs.SC↗

arXiv2018

A fast algorithm for solving linearly recurrent sequences

We present an algorithm which computes the $D^{th}$ term of a sequence satisfying a linear recurrence relation of order $d$ over a field $K$ in $O( \mathsf{M}(\bar d)\log(D) + \mathsf{M}(d)\log(d))$ operations in $K$, where $\bar d \leq d$ is the degree of the squarefree part of the annihilating polynomial of the recurrence and $\mathsf{M}$ is the cost of polynomial multiplication in $K$. This is a refinement of the previously optimal result of $O( \mathsf{M}(d)\log(D) )$ operations, due to Fiduccia.

cs.SC↗