Separating linear forms for bivariate systems

We present an algorithm for computing a separating linear form of a system of bivariate polynomials with integer coefficients, that is a linear combination of the variables that takes different values when evaluated at distinct (complex) solutions of the system. In other words, a separating linear form defines a shear of the coordinate system that sends the algebraic system in generic position, in the sense that no two distinct solutions are vertically aligned. The computation of such linear forms is at the core of most algorithms that solve algebraic systems by computing rational parameterizations of the solutions and, moreover, the computation a separating linear form is the bottleneck of these algorithms, in terms of worst-case bit complexity. Given two bivariate polynomials of total degree at most $d$ with integer coefficients of bitsize at most~$\tau$, our algorithm computes a separating linear form in $\sOB(d^{8}+d^7\tau)$ bit operations in the worst case, where the previously known best bit complexity for this problem was $\sOB(d^{10}+d^9\tau)$ (where $\sO$ refers to the complexity where polylogarithmic factors are omitted and $O_B$ refers to the bit complexity).

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Field Value
Source https://inria.hal.science/hal-00802693
Author Bouzidi, Yacine, Lazard, Sylvain, Pouget, Marc, Rouillier, Fabrice
Maintainer CCSD
Last Updated May 7, 2026, 08:40 (UTC)
Created May 7, 2026, 08:40 (UTC)
Identifier Report N°: RR-8261
Language en
Rights https://about.hal.science/hal-authorisation-v1/
contributor Effective Geometric Algorithms for Surfaces and Visibility (VEGAS) ; Centre Inria de l'Université de Lorraine ; Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Department of Algorithms, Computation, Image and Geometry (LORIA - ALGO) ; Laboratoire Lorrain de Recherche en Informatique et ses Applications (LORIA) ; Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Lorrain de Recherche en Informatique et ses Applications (LORIA) ; Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-CentraleSupélec-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
creator Bouzidi, Yacine
date 2013-03-20T00:00:00
harvest_object_id 582be8ce-3a8d-47ba-96a1-9e506ee66d57
harvest_source_id 3374d638-d20b-4672-ba96-a23232d55657
harvest_source_title test moissonnage SELUNE
metadata_modified 2025-11-04T00:00:00
relation info:eu-repo/semantics/altIdentifier/arxiv/1303.5041
set_spec type:REPORT