Generalized Analytic Functions

1. Some problems arising in the study of value distribution of functions of two complex variables. One of the objectives of modern analysis consists in the generalization of methods of the theory of functions of one complex variable in such a way that the procedures in the revised form can be applied in other fields, in particular, in the theory of functions of several complex variables, in the theory of partial differential equations, in differential geometry, etc. In this way one can hope to obtain in time a unified theory of various chapters of analysis. The method of the kernel function is one of the tools of this kind. In particular, this method permits us to develop some chapters of the theory of analytic and meromorphic functions f(z1, * * *, zn) of the class j2(I2n), various chapters in the theory of pseudo-conformal transformations (i.e., of transformations of the domains V2n by n analytic functions of n complex variables) etc. On the other hand, it is of considerable interest to generalize other chapters of the theory of functions of one variable, at first to the case of several complex variables. In particular, the study of value distribution of entire and meromorphic functions represents a topic of great interest. Generalizing the classical results about the zeros of a polynomial, Hadamard and Borel established a connection between the value distribution of a function and its growth. A further step of basic importance has been made by Nevanlinna and Ahlfors, who showed not only that the results of Hadamard and Borel in a sharper form can be obtained by using potential-theoretical and topological methods, but found in this way important new relations, and opened a new field in the modern theory of functions. As one passes from the theory of functions of one variable to the case of two and more variables(2), the question of the value distribution becomes more complex and many directions arise which can be considered as a generalization of the above mentioned chapter of the theory of functions of one variable. However, the formulation of the problems which can be answered, and generalization of methods used in one variable, is not immediate. A function of two complex variables may vanish in a domain on a segment

The theory of real functions is a relatively young chapter of mathematical analysis. In fact, in the 19th century, the expression “function theory” was applied to mean the theory of complex-valued analytic functions of one or more complex variables. The first investigations that initiated the part of analysis called today “theory of real functions” or briefly “real analysis” were constructions of various real-valued functions of a real variable whose characteristic properties are very far from those of analytic functions; as a typical example, we can mention the construction, due to Karl Weierstrass, of a real-valued function continuous in an interval but not differentiable at any point of this interval.

Some elements of a theory of multidimensional complex variables: part II. expansions of analytic functions and application to fluid flows

In the theory of analytic and univalent functions, coefficients of functions’ Taylor series representation and their related functional inequalities are of major interest and how they estimate functions’ growth in their specified domains. One of the important and useful functional inequalities is the Fekete-Szegö inequality. In this work, we aim to analyze the Fekete-Szegö functional and to find its upper bound for certain analytic functions which give parabolic and petal type regions as image domains. Coefficient inequalities and the Fekete-Szegö inequality of inverse functions to these certain analytic functions are also established in this work.

The theory of analytic functions of several complex variables enjoyed a period of remarkable development in the middle part of the twentieth century. After initial successes by Poincare and others in the late 19th and early 20th centuries, the theory encountered obstacles that prevented it from growing quickly into an analogue of the theory for functions of one complex variable. Beginning in the 1930s, initially through the work of Oka, then H. Cartan, and continuing with the work of Grauert, Remmert, and others, new tools were introduced into the theory of several complex variables that resolved many of the open problems and fundamentally changed the landscape of the subject. These tools included a central role for sheaf theory and increased uses of topology and algebra. The book by Gunning and Rossi was the first of the modern era of the theory of several complex variables, which is distinguished by the use of these methods. The intention of Gunning and Rossi's book is to provide an extensive introduction to the Oka-Cartan theory and some of its applications, and to the general theory of analytic spaces. Fundamental concepts and techniques are discussed as early as possible. The first chapter covers material suitable for a one-semester graduate course, presenting many of the central problems and techniques, often in special cases. The later chapters give more detailed expositions of sheaf theory for analytic functions and the theory of complex analytic spaces. Since its original publication, this book has become a classic resource for the modern approach to functions of several complex variables and the theory of analytic spaces.

This paper deals with the solutions of linear inhomogeneous time-fractional partial differential equations in applied mathematics and fluid mechanics. The fractional derivatives are described in the Caputo sense. The fractional Green function method is used to obtain solutions for time-fractional wave equation, linearized time-fractional Burgers equation, and linear time-fractional KdV equation. The new approach introduces a promising tool for solving fractional partial differential equations.

This paper shows that the method of ‘reduction of order’ is both a simpler way of teaching and of obtaining solutions for inhomogeneous linear ordinary differential equations than is the normally espoused method of ‘variation of parameters’. Details are given of the results of the method for the general nth order equation and the two methods are compared for n = 2, 3. It will be noted that the proposed method takes a particularly simple form when the right‐hand side of the equation is a multiple of one of the solutions to the related homogeneous equation.

In 1967 Roger Penrose introduced what is now called twistor geometry (Penrose 1967). This geometry is an amplification of the geometry of lines in projective space studied extensively by Felix Klein and others in the late 19th century. Penrose made the fundamental observation that this classical geometry could be used in conjunction with a Radon transform style integral geometry to provide rather complete sets of solutions of numerous partial differential equations, both linear and nonlinear, which arise naturally in theoretical physics. The Radon transform, which involves integration over straight lines in R 3, was used by F. John to generate solutions of hyperbolic partial differential equations in 1942. Penrose integrates over complex projective lines, real 2-spheres, and the data of the integration is complex-analytic functions of 3 complex variables. This is analogous to (and indeed related to) Weierstrass' representation of solutions of the minimal surface equation in terms of triples of holomorphic functions of a single complex variable which satisfy an algebraic relation. In this paper we discuss the origins of the differential equations which are amiable to twistor-geometric study from the realms of theoretical physics. Twistor geometry is most suitable for physical theories which are relativistically invariant, including Maxwell's description of electromagnetic phenomena from the 19th century (Maxwell's equations), Einstein's theory of gravitation (the equations of general relativity), and the contemporary descriptions of elementary particles (quantum field theory). Twistor geometry interacts in a nontrivial manner with the mathematical models involved in all of the above physical theories. In particular, it has led to new solutions of some of the nonlinear partial differential equations involved (Einstein's equations, Yang-Mills equations, equations of a magnetic monopole). We will describe some recent progress on twistorgeometric representations of solutions of classical field equations. There are two aspects to this. First, there is the problem of translating a given system of differential equations into twistor-geometric language. This has been done successfully in many different cases, and will be described in Section 3. Once a given problem has been transferred to a twistor-geometric context, it becomes, in general, a specific problem involving algebraic geometry, several complex variables, and algebraic topology involving holomorphic data on complex manifolds. The only partial differential equations remaining in the twistor context are the CauchyRiemann equations characterizing holomorphic functions. In effect, the partial differential equation has been transformed into a geometric problem. This is analogous to the Fourier transform transforming a partial differential equation with constant coefficients into an algebraic problem, where differentiation is replaced by the (algebraic) symbol of the differential operator in question. The second aspect of the recent progress on the twistor-geometric representation of the solutions of the classical field equations concerns itself with solving the geometric problem in question and transforming back to space-time (or Euclidean space), generating (sometimes new) solutions of the classical field equations.

The theory of analytical functions is widely used not only in fundamental research. It is a universal tool that allows you to formalize physical phenomena, facilitate the analysis of complex systems, solve complex physical problems, increasing the accuracy and efficiency of the results. With the help of analytical functions, many problems are reduced to simpler formulas that are easily interpreted. It also becomes possible to obtain analytical solutions without numerical methods, and the Cauchy-Riemann equations allow you to simultaneously describe several physical characteristics. In particular, in electrodynamics and field theory, analytical functions are used to describe potentials and fields, and the conformal mappings they perform are used to determine the distribution of the electric field in complex geometric regions, for example, around an electrode in the form of a corner or near sharp edges. In this article, an analytical function called the complex potential is used to determine the characteristics of the electrostatic field of flat and cylindrical capacitors. In particular, by studying the complex potential of the electrostatic field of flat and cylindrical capacitors, families of equipotentials and flux lines were obtained for them, the direction of the electrostatic field strength vector E was determined, and the capacitance C was calculated for these types of capacitors. It is indicated that the electrostatic field strength vector E of a flat capacitor is constant and directed normal to the surface of the capacitor plates, and in the case of a cylindrical capacitor, the vectors E and D (electrostatic induction vector) are directed radially from the inner cylinder (r = a) to the outer (r = b), if the inner one has a positive charge).

Motivation. Analytic function theory on commutative complex extensions calls for an operator–theoretic calculus that simultaneously sees the algebra-induced coupling among components and supports boundary-to-interior mechanisms. Gap. While Dirac-type frameworks are classical in several complex variables and Clifford analysis, a coherent calculus aligning structural CR systems, a canonical first derivative, and a Cauchy-type boundary identity on the commutative model C(C)≅C4 has not been systematically developed. Purpose and Aims. This paper develops such a calculus for O-regular mappings on C(C) and establishes three pillars of the theory. Main Results. (i) A fully coupled Cauchy–Riemann system characterizing O-regularity; (ii) identification of a canonical first derivative g′(z)=∂x0g(z); and (iii) a Stokes-driven boundary annihilation law ∫∂Ωτg=0 for a canonical 7-form τ. On (pseudo)convex domains, ∂¯-methods yield solvability under natural compatibility and regularity assumptions. Stability (under algebra-preserving maps), Liouville-type, and removability results are also obtained, and function spaces suited to this algebra are outlined. Significance. The results show that a large portion of the classical holomorphic toolkit survives, in algebra-aware form, on C(C).

We propose a one-dimensional lattice theory scheme based on a coupled optomechanical system consisting of multiple cavity field modes and mechanical modes, where their frequencies can be tuned. In this system, by manipulating parameters to obtain collective dynamical evolution of the system, we study topological properties and topological quantum channels in the system. Firstly, the topological insulator properties and topological quantum channels of the system are studied by modulating the periodic coupling parameters of the system and analyzing the characteristics of the energy spectrum and edge states of the system. It is found that edge state distributions can exhibit flipping processes, which can be applied to quantum information processing. Secondly, based on the scattering theory of topological insulators and the relationship between input and output, the variation characteristics of the steady-state average photon number of the cavity field and the winding number of the reflection coefficient phase are analyzed. It is found that the dissipation of the cavity field has a certain influence on the locality of the distribution of the average photon number in the lattice, and it also indirectly explains the locality of the edge states of the system, and the topological invariants are detected by the winding number. In addition, considering the effect of disordered defects on topological properties, we further analyze their effects on the energy spectrum of the system, the winding number of the reflection coefficient phase and the average photon number of the cavity field. It is found that two defects in the system cause different physical effects, and when their values are small, the edge states of the system are robust to it, which also shows that the system has the characteristics of topological protection. However, when disorder and perturbation are larger than the energy gap, the topological properties of the system will be annihilated, so that the edge states will be indistinguishable, and the topological invariants will change at the same time. The research results of this system can be generalized to other types of models and can be applied to quantum communication and quantum information processing, which will have certain constructive suggestions for the development of future quantum technology.

The particular solutions of inhomogeneous differential equations with polynomial coefficients in terms of the Green’s function are obtained in the framework of distribution theory. In particular, discussions are given on Kummer’s and the hypergeometric differential equation. Related discussions are given on the particular solution of differential equations with constant coefficients, by the Laplace transform.

We prove that if an analytic function f with an isolated singular point at ∞ is a solution of the differential equation P(zlnz, f, f′) = 0, where P is a polynomial in all variables, then f has finite order. We study the asymptotic properties of a meromorphic solution with logarithmic singularity.

Zero modes of velocity field and topological invariant in quantum torus

Analytical function theory approach to the heat transfer problem of a cylinder in cross-flow at small Péclet numbers