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A certified iterative method for isolated singular roots

Angelos Mantzaflaris 1 Bernard Mourrain 1 Agnes Szanto 2
1 AROMATH - AlgebRe, geOmetrie, Modelisation et AlgoriTHmes
CRISAM - Inria Sophia Antipolis - Méditerranée , NKUA - National and Kapodistrian University of Athens
Abstract : In this paper we provide a new method to certify that a nearby polynomial system has a singular isolated root and we compute its multiplicity structure. More precisely, given a polynomial system f = (f1 ,. .. , fN) ∈ C[x1 ,. .. , xn ]^N , we present a Newton iteration on an extended deflated system that locally converges, under regularity conditions, to a small deformation of f such that this deformed system has an exact singular root. The iteration simultaneously converges to the coordinates of the singular root and the coefficients of the so-called inverse system that describes the multiplicity structure at the root. We use α-theory test to certify the quadratic convergence, and to give bounds on the size of the deformation and on the approximation error. The approach relies on an analysis of the punctual Hilbert scheme, for which we provide a new description. We show in particular that some of its strata can be rationally parametrized and exploit these parametrizations in the certification. We show in numerical experimentation how the approximate inverse system can be computed as a starting point of the Newton iterations and the fast numerical convergence to the singular root with its multiplicity structure, certified by our criteria.
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Preprints, Working Papers, ...
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https://hal.archives-ouvertes.fr/hal-03079910
Contributor : Bernard Mourrain Connect in order to contact the contributor
Submitted on : Thursday, December 17, 2020 - 2:12:09 PM
Last modification on : Wednesday, January 27, 2021 - 8:49:01 AM
Long-term archiving on: : Thursday, March 18, 2021 - 8:42:03 PM

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  • HAL Id : hal-03079910, version 1

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Angelos Mantzaflaris, Bernard Mourrain, Agnes Szanto. A certified iterative method for isolated singular roots. 2020. ⟨hal-03079910⟩

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