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Multivariate polynomial inequalities viapluripotential theory and subanalytic geometry methods

W. Pleśniak (2006)

Banach Center Publications

We give a state-of-the-art survey of investigations concerning multivariate polynomial inequalities. A satisfactory theory of such inequalities has been developed due to applications of both the Gabrielov-Hironaka-Łojasiewicz subanalytic geometry and pluripotential methods based on the complex Monge-Ampère operator. Such an approach permits one to study various inequalities for polynomials restricted not only to nice (nonpluripolar) compact subsets of ℝⁿ or ℂⁿ but also their versions for pieces...

Non-isotropic Hausdorff capacity of exceptional sets for pluri-Green potentials in the unit ball of ℂⁿ

Kuzman Adzievski (2006)

Annales Polonici Mathematici

We study questions related to exceptional sets of pluri-Green potentials V μ in the unit ball B of ℂⁿ in terms of non-isotropic Hausdorff capacity. For suitable measures μ on the ball B, the pluri-Green potentials V μ are defined by V μ ( z ) = B l o g ( 1 / | ϕ z ( w ) | ) d μ ( w ) , where for a fixed z ∈ B, ϕ z denotes the holomorphic automorphism of B satisfying ϕ z ( 0 ) = z , ϕ z ( z ) = 0 and ( ϕ z ϕ z ) ( w ) = w for every w ∈ B. If dμ(w) = f(w)dλ(w), where f is a non-negative measurable function of B, and λ is the measure on B, invariant under all holomorphic automorphisms of B, then V μ ...

On extremal holomorphically contractible families

Marek Jarnicki, Witold Jarnicki, Peter Pflug (2003)

Annales Polonici Mathematici

We prove (Theorem 1.2) that the category of generalized holomorphically contractible families (Definition 1.1) has maximal and minimal objects. Moreover, we present basic properties of these extremal families.

On perturbations of pluriregular sets generated by sequences of polynomial maps

Maciej Klimek (2003)

Annales Polonici Mathematici

It is shown that an infinite sequence of polynomial mappings of several complex variables, with suitable growth restrictions, determines a filled-in Julia set which is pluriregular. Such sets depend continuously and analytically on the generating sequences, in the sense of pluripotential theory and the theory of set-valued analytic functions, respectively.

On Pólya's Theorem in several complex variables

Ozan Günyüz, Vyacheslav Zakharyuta (2015)

Banach Center Publications

Let K be a compact set in ℂ, f a function analytic in ℂ̅∖K vanishing at ∞. Let f ( z ) = k = 0 a k z - k - 1 be its Taylor expansion at ∞, and H s ( f ) = d e t ( a k + l ) k , l = 0 s the sequence of Hankel determinants. The classical Pólya inequality says that l i m s u p s | H s ( f ) | 1 / s ² d ( K ) , where d(K) is the transfinite diameter of K. Goluzin has shown that for some class of compacta this inequality is sharp. We provide here a sharpness result for the multivariate analog of Pólya’s inequality, considered by the second author in Math. USSR Sbornik 25 (1975), 350-364.

On the Bergman distance on model domains in ℂⁿ

Gregor Herbort (2016)

Annales Polonici Mathematici

Let P be a real-valued and weighted homogeneous plurisubharmonic polynomial in n - 1 and let D denote the “model domain” z ∈ ℂⁿ | r(z):= Re z₁ + P(z’) < 0. We prove a lower estimate on the Bergman distance of D if P is assumed to be strongly plurisubharmonic away from the coordinate axes.

On the Green function on a certain class of hyperconvex domains

Gregor Herbort (2008)

Annales Polonici Mathematici

We study the behavior of the pluricomplex Green function on a bounded hyperconvex domain D that admits a smooth plurisubharmonic exhaustion function ψ such that 1/|ψ| is integrable near the boundary of D, and moreover satisfies the estimate | ψ | C e x p ( - C ' ( l o g ( 1 / δ D ) ) α ) at points close enough to the boundary with constants C,C’ > 0 and 0 < α < 1. Furthermore, we obtain a Hopf lemma for such a function ψ. Finally, we prove a lower bound on the Bergman distance on D.

On the multivariate transfinite diameter

Thomas Bloom, Jean-Paul Calvi (1999)

Annales Polonici Mathematici

We prove several new results on the multivariate transfinite diameter and its connection with pluripotential theory: a formula for the transfinite diameter of a general product set, a comparison theorem and a new expression involving Robin's functions. We also study the transfinite diameter of the pre-image under certain proper polynomial mappings.

Quantitative estimates for the Green function and an application to the Bergman metric

Klas Diederich, Gregor Herbort (2000)

Annales de l'institut Fourier

Let D n be a bounded pseudoconvex domain that admits a Hölder continuous plurisubharmonic exhaustion function. Let its pluricomplex Green function be denoted by G D ( . , . ) . In this article we give for a compact subset K D a quantitative upper bound for the supremum sup z K | G D ( z , w ) | in terms of the boundary distance of K and w . This enables us to prove that, on a smooth bounded regular domain D (in the sense of Diederich-Fornaess), the Bergman differential metric B D ( w ; X ) tends to infinity, for X n / { O } , when w D tends to a boundary point....

Random polynomials and (pluri)potential theory

Thomas Bloom (2007)

Annales Polonici Mathematici

For certain ensembles of random polynomials we give the expected value of the zero distribution (in one variable) and the expected value of the distribution of common zeros of m polynomials (in m variables).

Regularity of certain sets in ℂⁿ

Nguyen Quang Dieu (2003)

Annales Polonici Mathematici

A subset K of ℂⁿ is said to be regular in the sense of pluripotential theory if the pluricomplex Green function (or Siciak extremal function) V K is continuous in ℂⁿ. We show that K is regular if the intersections of K with sufficiently many complex lines are regular (as subsets of ℂ). A complete characterization of regularity for Reinhardt sets is also given.

Sets in N with vanishing global extremal function and polynomial approximation

Józef Siciak (2011)

Annales de la faculté des sciences de Toulouse Mathématiques

Let Γ be a non-pluripolar set in N . Let f be a function holomorphic in a connected open neighborhood G of Γ . Let { P n } be a sequence of polynomials with deg P n d n ( d n &lt; d n + 1 ) such that lim sup n | f ( z ) - P n ( z ) | 1 / d n &lt; 1 , z Γ . We show that if lim sup n | P n ( z ) | 1 / d n 1 , z E , where E is a set in N such that the global extremal function V E 0 in N , then the maximal domain of existence G f of f is one-sheeted, and lim sup n f - P n K 1 d n &lt; 1 for every compact set K G f . If, moreover, the sequence { d n + 1 / d n } is bounded then G f = N .If E is a closed set in N then V E 0 if and only if each series of homogeneous polynomials j = 0 Q j , for which some subsequence { s n k } ...

Siciak's extremal function in complex and real analysis

W. Pleśniak (2003)

Annales Polonici Mathematici

The Siciak extremal function establishes an important link between polynomial approximation in several variables and pluripotential theory. This yields its numerous applications in complex and real analysis. Some of them can be found on a rich list drawn up by Klimek in his well-known monograph "Pluripotential Theory". The purpose of this paper is to supplement it by applications in constructive function theory.

Siciak’s extremal function via Bernstein and Markov constants for compact sets in N

Leokadia Bialas-Ciez (2012)

Annales Polonici Mathematici

The paper is concerned with the best constants in the Bernstein and Markov inequalities on a compact set E N . We give some basic properties of these constants and we prove that two extremal-like functions defined in terms of the Bernstein constants are plurisubharmonic and very close to the Siciak extremal function Φ E . Moreover, we show that one of these extremal-like functions is equal to Φ E if E is a nonpluripolar set with l i m n M ( E ) 1 / n = 1 where M ( E ) : = s u p | | | g r a d P | | | E / | | P | | E , the supremum is taken over all polynomials P of N variables of total...

Siciak-Zahariuta extremal functions and polynomial hulls

Finnur Lárusson, Ragnar Sigurdsson (2007)

Annales Polonici Mathematici

We use our disc formula for the Siciak-Zahariuta extremal function to characterize the polynomial hull of a connected compact subset of complex affine space in terms of analytic discs.

The Siciak-Zahariuta extremal function as the envelope of disc functionals

Finnur Lárusson, Ragnar Sigurdsson (2005)

Annales Polonici Mathematici

We establish disc formulas for the Siciak-Zahariuta extremal function of an arbitrary open subset of complex affine space. This function is also known as the pluricomplex Green function with logarithmic growth or a logarithmic pole at infinity. We extend Lempert's formula for this function from the convex case to the connected case.

Two remarks on the Suita conjecture

Nikolai Nikolov (2015)

Annales Polonici Mathematici

It is shown that the weak multidimensional Suita conjecture fails for any bounded non-pseudoconvex domain with C 1 + ε -smooth boundary. On the other hand, it is proved that the weak converse to the Suita conjecture holds for any finitely connected planar domain.

Weighted Bernstein-Markov property in ℂⁿ

Nguyen Quang Dieu, Pham Hoang Hiep (2012)

Annales Polonici Mathematici

We study the weighted Bernstein-Markov property for subsets in ℂⁿ which might not be bounded. An application concerning approximation of the weighted Green function using Bergman kernels is also given.

Weighted pluripotential theory on compact Kähler manifolds

Maritza M. Branker, Małgorzata Stawiska (2009)

Annales Polonici Mathematici

We introduce a weighted version of the pluripotential theory on compact Kähler manifolds developed by Guedj and Zeriahi. We give the appropriate definition of a weighted pluricomplex Green function, its basic properties and consider its behavior under holomorphic maps. We also develop a homogeneous version of the weighted theory and establish a generalization of Siciak's H-principle.

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