SOS approximations of nonnegative polynomials via simple high degree perturbation

dc.creatorLasserre, Jean B.
dc.creatorNetzer, Tim
dc.date2005-10-21
dc.date.accessioned2026-07-07T06:47:45Z
dc.date.available2026-07-07T06:47:45Z
dc.descriptionWe show that every real polynomial $f$ nonnegative on $[-1,1]^{n}$ can be approximated in the $l_{1}$-norm of coefficients, by a sequence of polynomials $\{f_{\ep r}\}$ that are sums of squares. This complements the existence of s.o.s. approximations in the denseness result of Berg, Christensen and Ressel, as we provide a very simple and \textit{explicit} approximation sequence. Then we show that if the Moment Problem holds for a basic closed semi-algebraic set $K_S\subset\R^n$ with nonempty interior, then every polynomial nonnegative on $K_S$ can be approximated in a similar fashion by elements from the corresponding preordering. Finally, we show that the degree of the perturbation in the approximating sequence depends on $ε$ as well as the degree and the size of coefficients of the nonnegative polynomial $f$, but not on the specific values of its coefficients.
dc.description12 pages
dc.identifierhttps://arxiv.org/abs/math/0510456
dc.identifierhttp://arxiv.org/abs/math/0510456
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/103757
dc.subjectAlgebraic Geometry
dc.subject12E05, 12Y05, 90C22, 44A60
dc.titleSOS approximations of nonnegative polynomials via simple high degree perturbation
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