Algebraic independence of logarithmic singularities of some complex functions

We show that algebraic independence of some complex functions of one variable over regular functions implies their algebraic independence over a larger ring, containing complex powers of regular functions. Based on this we obtain a generalization of a special case of the theorem of Kaczorowski and Perelli on functional independence of logarithms of functions in the Selberg class. As an application we state a new result on oscillations of arithmetical functions.     

左非奇异左CS-环和左遗传左CS-环

本文首先证明了：环为左非奇异左CS-环当且仅当它为左余非奇异Baer环,然后给出左遗传左CS-环,正则左遗传左CS-环和左遗传左连续环的某些刻划.     

Universal Abelian covers of rational surface singularities and multi-index filtrations

In previous papers, the authors computed the Poincaré series of some (multi-index) filtrations on the ring of germs of functions on a rational surface singularity. These Poincaré series were expressed as the integer parts of certain fractional power series, whose interpretation was not given. In this paper, we show that, up to a simple change of variables, these fractional power series are reductions of the equivariant Poincaré series for filtrations on the ring of germs of functions on the universal Abelian cover of the surface. We compute these equivariant Poincaré series.     

Metric critical point theory: Potential Well Theorem and its applications

Recent results show evidence of the fact that the notion of critical point has a purely metric nature. In this paper, after giving the fundamental definitions of critical and regular points for continuous functions, we survey some applications of the nonsmooth critical point theory. Our basic tool is a Potential Well Theorem. Conferenza tenuta da A. Ioffe il 9 ottobre 1995     

Approximation by polynomials on quaternionic compact sets

In this paper, we obtain several extensions to the quaternionic setting of some results concerning the approximation by polynomials of functions continuous on a compact set and holomorphic in its interior. To this end, we prove an analog of the Riemann mapping theorem for a subclass of open sets, whose validity involves precisely the slice regular functions for which the composition remains slice regular. The results include approximation on compact starlike sets and compact axially symmetric sets. The cases of some concrete particular sets are described in details, including also quantitative estimates. Copyright © 2014 John Wiley & Sons, Ltd.     

Alexander polynomials and Poincaré series of sets of ideals

Earlier the authors considered and, in some cases, computed Poincaré series for two sorts of multi-index filtrations on the ring of germs of functions on a complex (normal) surface singularity (in particular, on the complex plane). A filtration of the first class was defined by a curve (with several branches) on the surface singularity. A filtration of the second class (called divisorial) was defined by a set of components of the exceptional divisor of a modification of the surface singularity. Here we define and compute in some cases the Poincaré series corresponding to a set of ideals in the ring of germs of functions on a surface singularity. For the complex plane, this notion unites the two classes of filtrations described above.     

The Poincaré series of divisorial valuations in the plane defines the topology of the set of divisors

With a plane curve singularity one associates a multi-index filtration on the ring of germs of functions of two variables defined by the orders of a function on irreducible components of the curve. The Poincaré series of this filtration turns out to coincide with the Alexander polynomial of the curve germ. For a finite set of divisorial valuations on the ring corresponding to some components of the exceptional divisor of a modification of the plane, in a previous paper there was obtained a formula for the Poincaré series of the corresponding multi-index filtration similar to the one associated with plane germs. Here we show that the Poincaré series of a set of divisorial valuations on the ring of germs of functions of two variables defines “the topology of the set of the divisors” in the sense that it defines the minimal resolution of this set up to combinatorial equivalence. For the plane curve singularity case, we also give a somewhat simpler proof of the statement by Yamamoto which shows that the Alexander polynomial is equivalent to the embedded topology.     

The Symmetric Fourth Painlevé Hierarchy and Associated Special Polynomials

In this paper two families of rational solutions and associated special polynomials for the equations in the symmetric fourth Painlevé hierarchy are studied. The structure of the roots of these polynomials is shown to be highly regular in the complex plane. Further representations are given of the associated special polynomials in terms of Schur functions. The properties of these polynomials are compared and contrasted with the special polynomials associated with rational solutions of the fourth Painlevé equation.     

On almost monotonic real functions

The notion of regular subrings of a differential ring is defined. We prove that, for some element y of the ring satisfying certain conditions, the extension R₀[y] of a regular subring R₀ is also a regular subring. As an application, we give some results concerning almost monotonic real functions.     

Simultaneous residue interpolation problems for rational matrix functions

In this paper we give necessary and sufficient conditions for the consistency of a collection of interpolation conditions on a rational matrix function expressed in terms of residues. Such representations are a compact way of expressing tangential (or directional) interpolation conditions of arbitrarily high multiplicity possibly from both sides simultaneously. The main tool is some machinery developed earlier by the authors in connection with characterizing least common minimal multiples and greatest common minimal divisors for a collection of regular rational matrix functions.     

Multivariate generalized inverse vector-valued rational interpolants

Bivariate rational interpolating functions of the type introduced in [9, 1] are shown to have a natural extension to the case of rational interpolation of vector-valued quantities using the formalism of Graves-Morris [2]. In this paper, the convergence of Stieltjes-type branched vector-valued continued fractions for two-variable functions are constructed by using the Samelson inverse. Based on them, a kind of bivariate vector-valued rational interpolating function is defined on plane grids. Sufficient conditions for existence, characterisation and uniqueness for the interpolating functions are proved. The results in the paper are illustrated with some examples.     

多层前向正则模糊神经网络的逼近能力

Abstract. Four-layer feedforward regular fuzzy neural networks are constructed. Universal ap-proximations to some continuous fuzzy functions defined on (R)“ by the four-layer fuzzyneural networks are shown. At first,multivariate Bernstein polynomials associated with fuzzyvalued functions are empolyed to approximate continuous fuzzy valued functions defined on eachcompact set of R“. Secondly,by introducing cut-preserving fuzzy mapping,the equivalent condi-tions for continuous fuzzy functions that can be arbitrarily closely approximated by regular fuzzyneural networks are shown. Finally a few of sufficient and necessary conditions for characteriz-ing approximation capabilities of regular fuzzy neural networks are obtained. And some concretefuzzy functions demonstrate our conclusions.     

半平面中解析函数的积分表示及在逼近中的应用

在该文中, 作者证明了满足一定增长性条件的右半平面上的解析函数可以由它在边界上的积分和其加权Blaschke乘积的和表示, 作为应用, 作者还考虑了指数多项式在实数轴上加权 Banach 空间C_α 中的完备性.     

On some measures of noncompactness in the space of continuous functions

We consider some quantities in the space of functions continuous on a bounded interval, which are related to monotonicity of functions. Based on those quantities we construct a few measures of noncompactness in the mentioned function space. Several properties of those measures are established; among others it is shown that they are regular or “partly” regular measures and equivalent to the Hausdorff measure of noncompactness.     

Boundary properties for several singular integral operators in real Clifford analysis

On the basis of the Cauchy integral formulas for regular and biregular functions, we define some Cauchy-type singular integral operators. Then we discuss the Hlder continuous property of some singular integral operators with one integral variable. Then we divide a singular integral operator with two variables into three parts and prove its Hlder continuous property on the boundary.     

Dimension de Hausdorff du graphe d'une fonction continue : nouvelles majorations déterministes et minorations presque sûres

In this Note, we establish an upper bound of the Hausdorff dimension of the graph of a continuous function depending on its wavelet coefficients in a sufficiently regular wavelet basis. In particular, this bound is related to the Besov smoothness of the function. An almost sure lower bound of the same quantity is stated for some precise classes of random functions.     

一类具一阶奇性核的奇异积分方程

当(?)是复平面C上的光滑封闭曲线,k（z）是在(?)所围成的有界闭区域上连续.在其内部解析的函数时.借助于奇异积分算子的广义逆.讨论了具一阶奇性核的正则型奇异积分方程:　在H类中的求解问题.作为应用,作者给出了当k（z）是一类有理函数时的具体解法,从而统一并推广了 Cauchy核和Hilbert核奇异积分方程的经典结果.     

Morphic环和G-morphic环的一些结果

讨论了morphic环,G-morphic环,PP环,GPP环,Bear环与正则环之间的关系.还证明了在约化环中,强正则环,正则环,π-正则环,G-π-正则环的等价性.     

Computation of k1 Via mennicke symbols

For any ring A, the group K₁A is filtered by the Whitehead determinants of invertible matrices over A of different sizes. We want to compute the corresponding graded group (especially the highest degree non-zero term) in terms of symbols which generalize Mennicke’s symbol. In particular, we generalize the Bass-Milnor-Serre result which presents SK₁A of a Dedekind ring A via the Mennicke symbol, to an arbitrary commutative ring A satisfying the Bass second stable range condition. As an application, SK₁ is computed for some rings of continuous functions. Some of our theorems are partially known, but we have often weakened hypotheses, using stable range conditions rather than Krull dimension (having in mind applications to rings of continuous functions).     

Schröder iteration functions associated with a one-parameter family of biquadratic polynomials

Schröder iteration functions, a generalization of the Newton–Raphson method to determine roots of equations, are generally rational functions which possess some critical points, free to converge to attracting cycles. These free critical points, however, satisfy some higher-degree polynomial equations which we solve analytically. Then, with the help of microcomputer plots, we examine the Julia sets of the Schröder functions and the orbits of all their free critical points associated with a particular one-parameter family of quartic polynomials, by walking in their dynamic and parameter spaces. This examination takes place in the complex plane as well as on the Riemann sphere.