HERMITIAN COMPLEXITY OF REAL POLYNOMIAL IDEALS

2012 ◽  
Vol 23 (06) ◽  
pp. 1250026 ◽  
Author(s):  
JOHN P. D'ANGELO ◽  
MIHAI PUTINAR
Keyword(s):  
Necessary Conditions ◽  
Complex Geometry ◽  
Polynomial Optimization ◽  
Symmetric Polynomial ◽  
Holomorphic Maps ◽  
Real Polynomial ◽  
Algebraic Subset ◽  
Algebraic Set ◽  
Holomorphic Embedding

We define the Hermitian complexity of a real polynomial ideal and of a real algebraic subset of Cn. This concept is aimed at determining precise necessary conditions for a Hermitian symmetric polynomial to agree with a Hermitian squared norm on an algebraic set. The latter topic has been a central theme in modern polynomial optimization and in complex geometry, specifically related to the holomorphic embedding of pseudoconvex domain into balls, or the classification of proper holomorphic maps between balls.

scholarly journals On the Cardinality of A Semi-Algebraic Set

1994 ◽  
Vol 1 (3) ◽  
pp. 277-286
Author(s):  
G. Khimshiashvili
Keyword(s):  
Quadratic Forms ◽  
Real Closed Field ◽  
Closed Field ◽  
Algebraic Subset ◽  
Algebraic Set

Abstract It is shown that the cardinality of a finite semi-algebraic subset over a real closed field can be computed in terms of signatures of effectively constructed quadratic forms.

Equations and Complexity for the Dubois–Efroymson Dimension Theorem

2009 ◽  
Vol 52 (2) ◽  
pp. 224-236
Author(s):  
Riccardo Ghiloni
Keyword(s):  
Real Closed Field ◽  
Closed Field ◽  
Algebraic Subset ◽  
Algebraically Closed Field ◽  
Algebraic Set ◽  
Real Algebraic Set ◽  
Nonsingular Point ◽  
Minimum Integer ◽  
The Ideal

AbstractLetRbe a real closed field, letX⊂Rnbe an irreducible real algebraic set and letZbe an algebraic subset ofXof codimension ≥ 2. Dubois and Efroymson proved the existence of an irreducible algebraic subset ofXof codimension 1 containingZ. We improve this dimension theorem as follows. Indicate by μ the minimum integer such that the ideal of polynomials inR[x1, … ,xn] vanishing onZcan be generated by polynomials of degree ≤ μ. We prove the following two results: (1) There exists a polynomialP∈R[x1, … ,xn] of degree≤ μ+1 such thatX∩P–1(0) is an irreducible algebraic subset ofXof codimension 1 containingZ. (2) LetFbe a polynomial inR[x1, … ,xn] of degreedvanishing onZ. Suppose there exists a nonsingular pointxofXsuch thatF(x) = 0 and the differential atxof the restriction ofFtoXis nonzero. Then there exists a polynomialG∈R[x1, … ,xn] of degree ≤ max﹛d, μ + 1﹜ such that, for eacht∈ (–1, 1) \ ﹛0﹜, the set ﹛x∈X|F(x) +tG(x) = 0﹜ is an irreducible algebraic subset ofXof codimension 1 containingZ. Result (1) and a slightly different version of result (2) are valid over any algebraically closed field also.

scholarly journals Curvature and the c-projective mobility of Kähler metrics with hamiltonian 2-forms

2016 ◽  
Vol 152 (8) ◽  
pp. 1555-1575 ◽  
Author(s):  
David M. J. Calderbank ◽  
Vladimir S. Matveev ◽  
Stefan Rosemann
Keyword(s):  
Necessary Conditions ◽  
Kähler Metrics ◽  
Kähler Metric ◽  
Kahler Metrics ◽  
Local Classification ◽  
Complex Cone ◽  
Kahler Metric ◽  
Cone Metric

The mobility of a Kähler metric is the dimension of the space of metrics with which it is c-projectively equivalent. The mobility is at least two if and only if the Kähler metric admits a nontrivial hamiltonian 2-form. After summarizing this relationship, we present necessary conditions for a Kähler metric to have mobility at least three: its curvature must have nontrivial nullity at every point. Using the local classification of Kähler metrics with hamiltonian 2-forms, we describe explicitly the Kähler metrics with mobility at least three and hence show that the nullity condition on the curvature is also sufficient, up to some degenerate exceptions. In an appendix, we explain how the classification may be related, generically, to the holonomy of a complex cone metric.

scholarly journals On holomorphic maps and Generalized Complex Geometry

2011 ◽  
Vol 61 (8) ◽  
pp. 1502-1515 ◽  
Author(s):  
Liviu Ornea ◽  
Radu Pantilie
Keyword(s):  
Complex Geometry ◽  
Holomorphic Maps ◽  
Generalized Complex

Potentially eventually positive star sign patterns

2016 ◽  
Vol 31 ◽  
pp. 541-548
Author(s):  
Yu Ber-Lin ◽  
Huang Ting-Zhu ◽  
Jie Cui ◽  
Deng Chunhua
Keyword(s):  
Positive Integer ◽  
Necessary Conditions ◽  
Positive Sign ◽  
Real Matrix ◽  
Sign Pattern ◽  
Positive Real ◽  
Sign Patterns

An $n$-by-$n$ real matrix $A$ is eventually positive if there exists a positive integer $k_{0}$ such that $A^{k}>0$ for all $k\geq k_{0}$. An $n$-by-$n$ sign pattern $\mathcal{A}$ is potentially eventually positive (PEP) if there exists an eventually positive real matrix $A$ with the same sign pattern as $\mathcal{A}$. An $n$-by-$n$ sign pattern $\mathcal{A}$ is a minimal potentially eventually positive sign pattern (MPEP sign pattern) if $\mathcal{A}$ is PEP and no proper subpattern of $\mathcal{A}$ is PEP. Berman, Catral, Dealba, et al. [Sign patterns that allow eventual positivity, {\it ELA}, 19(2010): 108-120] established some sufficient and some necessary conditions for an $n$-by-$n$ sign pattern to allow eventual positivity and classified the potentially eventually positive sign patterns of order $n\leq 3$. However, the identification and classification of PEP signpatterns of order $n\geq 4$ remain open. In this paper, all the $n$-by-$n$ PEP star sign patterns are classified by identifying all the MPEP star sign patterns.

Confidence through the semiotic process

Semiotica ◽  
2019 ◽  
Vol 2019 (228) ◽  
pp. 55-76
Author(s):  
Priscila Monteiro Borges
Keyword(s):  
Necessary Conditions ◽  
Reasoning Process ◽  
The Core ◽  
Level Of Confidence ◽  
Semiotic Process

AbstractPeirce’s semiotics is a formal doctrine of signs. As such, semiotics “would be concerned, in part, to determine the conditions for counting anything as true” (Liszka 1996: 2). Sometimes, semiotics is reduced to its first branch, speculative grammar, which concerns the classification of signs. However, critic and methodeutic are fundamental to guarantee the accuracy of the semiotic process. Critic gives “the conditions which determine the reasoning to be secure” (c.1902, CP 2.1) and methodeutic is the “study of the necessary conditions of the transmission of meaning by signs from mind to mind” (c.1897, CP 1.444). When we observe the system of sixty-six sign classes, we can find a method that provides confidence in the reasoning process. That means we can find classes of signs that represent critic and methodeutic in this system. The set of symbolic signs are the core of this process. In this paper, I will examine the interpretants of symbolic signs in order to describe the production of interpretants that increase the level of confidence in reasoning, contributing to the evolution of thought. The system of sixty-six sign classes provides a more complex set of interpretants, which might show the relation between the three branches of semiotics.

COHERENT SYSTEMS OF GENUS 0

2004 ◽  
Vol 15 (04) ◽  
pp. 409-424 ◽  
Author(s):  
H. LANGE ◽  
P. E. NEWSTEAD
Keyword(s):  
Moduli Spaces ◽  
Necessary Conditions ◽  
Projective Line ◽  
Coherent Systems

In this paper we begin the classification of coherent systems (E,V) on the projective line which are stable with respect to some value of a parameter α. In particular we show that the moduli spaces, if non-empty, are always smooth and irreducible of the expected dimension. We obtain necessary conditions for non-emptiness and, when dim V=1 or 2, we determine these conditions precisely. We also obtain partial results in some other cases.

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