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In this paper, we defined a new family of meromorphic functions whose analytic characterization was motivated by the definition of the multiplicative derivative. Replacing the ordinary derivative with a multiplicative derivative in the subclass of starlike meromorphic functions made the class redundant; thus, major deviation or adaptation was required in defining a class of meromorphic functions influenced by the multiplicative derivative. In addition, we redefined the subclass of meromorphic functions analogous to the class of the functions with respect to symmetric points. Initial coefficient estimates and Fekete–Szegö inequalities were obtained for the defined function classes. Some examples along with graphs have been used to establish the inclusion and closure properties. [ABSTRACT FROM AUTHOR]

Inequalities are essential in solving mathematical problems in many different areas of mathematics. Among these, problems involving coefficient combinations that occurred in the Taylor–Maclaurin series of the inverse of complex-valued analytic functions are the challenging ones to solve. In the current article, our aim is to study certain coefficient-related problems that construct from coefficients of the inverse of specific analytic functions. These problems include the Zalcman and Fekete–Szegö inequalities, as well as sharp estimates of the second and third-order Hankel determinants with inverse function coefficients. Also, one of the obtained results gives an improvement of the problem that has been recently published in the journal "AIMS Mathematics".

The main purpose of this work is to study the third Hankel determinant for classes of Bernoulli lemniscate-related functions by introducing new subclasses of star-like functions represented by S L λ * and R L λ . In many geometric and physical applications of complex analysis, estimating sharp bounds for problems involving the coefficients of univalent functions is very important because these coefficients describe the fundamental properties of conformal maps. In the present study, we defined sharp bounds for function-coefficient problems belonging to the family of S L λ * and R L λ . Most of the computed bounds are sharp. This study will encourage further research on the sharp bounds of analytical functions related to new image domains. [ABSTRACT FROM AUTHOR]

For the Poisson equation posed in a domain containing a large number of polygonal perforations, we propose a low-dimensional coarse approximation space based on a coarse polygonal partitioning of the domain. Similarly to other multiscale numerical methods, this coarse space is spanned by locally discrete harmonic basis functions. Along the subdomain boundaries, the basis functions are piecewise polynomial. The main contribution of this article is an error estimate regarding the H 1 -projection over the coarse space; this error estimate depends only on the regularity of the solution over the edges of the coarse partitioning. For a specific edge refinement procedure, the error analysis establishes superconvergence of the method even if the true solution has a low general regularity. Additionally, this contribution numerically explores the combination of the coarse space with domain decomposition (DD) methods. This combination leads to an efficient two-level iterative linear solver which reaches the fine-scale finite element error in few iterations. It also bodes well as a preconditioner for Krylov methods and provides scalability with respect to the number of subdomains. [ABSTRACT FROM AUTHOR]

Let B T 4 l denote a subclass of bounded turning functions connected with a four-leaf-type domain. The goal of the study is to probe into the bounds of coefficients | b 6 | , | b 7 | , | b 8 | , the bounds of the logarithmic coefficients, and the third-order determinants | H 3 , 1 | , | H 3 , 2 | , | H 3 , 3 | for the functions in this class. [ABSTRACT FROM AUTHOR]

We extend representation formulas that generalize the similarity principle of solutions to the Vekua equation to certain classes of meta-analytic functions. Also, we solve a generalization of the higher-order Schwarz boundary value problem in the context of meta-analytic functions with boundary conditions that are boundary values in the sense of distributions. [ABSTRACT FROM AUTHOR]

The time evolution of the mother body of a planar, uniform vortex that moves in an incompressible, inviscid fluid is investigated. The vortex is isolated, so that its motion is just due to self-induced velocities. Its mother body is defined as the part internal to the vortex of the singular set of the Schwarz function of its boundary. In the present analysis, it is an arc of curve (branch cut), starting and ending in the two internal branch points of this function, across any point of which the Schwarz function experiences a finite jump. By looking at the mother body from the outside of the vortex, it behaves as a vortex sheet having density of circulation given by the jump of the Schwarz function. Its name (mother body) is taken from Geophysics, and it is here used due to its property of generating, outside the vortex and on its boundary, the same velocity as the vortex itself. The shape of the branch cut and the jump of the Schwarz function across any point of it change in time, by following the motion of the vortex boundary. As it happens for a physical vortex sheet, the mother body is not a material line, so that it does not move according to the velocities induced by the vortex. In the present paper, the cut shape, the above jumps, as well as the cut velocities are deduced from the time evolution equation of the Schwarz function. Numerical experiments, carried out by building the branch cut and calculating the limit values of the Schwarz function on its sides during the vortex motion, confirm the analytical calculations. Some global quantities (circulation, first and second order moments) are here rewritten as integrals on the cut, and their conservation during the vortex motion is analytically and numerically verified. Indeed, the numerical simulations show that they behave in the same way as their classical contour dynamics forms, written in terms of integrals on the vortex boundary. This proves that the shape of the cut, as well as the limit values of the Schwarz function on its sides, are correctly calculated during the motion. [ABSTRACT FROM AUTHOR]

In this paper, we propose an efficient augmentation-based preconditioner for solving complex symmetric linear systems, which is obtained by augmenting the (2,2) block of the coefficient matrix. Then, the convergence of the corresponding iteration method is analyzed, and several spectral properties of the preconditioned matrices, such as eigenvalue distributions and eigenvectors, are also discussed. Numerical experiments demonstrate that our proposed preconditioner is more effective than some existing block preconditioners. [ABSTRACT FROM AUTHOR]

We investigate additive Schwarz methods for semilinear elliptic problems with convex energy functionals, which have wide scientific applications. A key observation is that the convergence rates of both one- and two-level additive Schwarz methods have bounds independent of the nonlinear term in the problem. That is, the convergence rates do not deteriorate by the presence of nonlinearity, so that solving a semilinear problem requires no more iterations than a linear problem. Moreover, the two-level method is scalable in the sense that the convergence rate of the method depends on H/h and H/δ only, where h and H are the typical diameters of an element and a subdomain, respectively, and δ measures the overlap among the subdomains. Numerical results are provided to support our theoretical findings. [ABSTRACT FROM AUTHOR]

Starlike and convex functions have gained increased prominence in both academic literature and practical applications over the past decade. Concurrently, logarithmic coefficients play a pivotal role in estimating diverse properties within the realm of analytic functions, whether they are univalent or nonunivalent. In this paper, we rigorously derive bounds for specific Toeplitz determinants involving logarithmic coefficients pertaining to classes of convex and starlike functions concerning symmetric points. Furthermore, we present illustrative examples showcasing the sharpness of these established bounds. Our findings represent a substantial contribution to the advancement of our understanding of logarithmic coefficients and their profound implications across diverse mathematical contexts. [ABSTRACT FROM AUTHOR]

A two-dimensional free boundary problem is formulated in which the normal velocity of the boundary is proportional to the inverse of the gradient of a harmonic function |$T$|⁠. The field |$T$| is defined in a simply connected region which includes the point at infinity where it has a logarithmic singularity. The growth problem in which the boundary expands outwards is formulated both in terms of the Schwarz function of the boundary and a Polubarinova–Galin equation for the conformal map of the region from the exterior of the unit disk. An expanding free boundary is shown to be stable and explicit solutions for growing ellipses and a class of polynomial lemniscates are derived. Numerical solution of the Polubarinova–Galin equation is used to compute the evolution of the boundary having other initial shapes. [ABSTRACT FROM AUTHOR]

Without qualms, studies show that quantum calculus has received great attention in recent times. This can be attributed to its wide range of applications in many science areas. In this exploration, we study a new qdifferential operator that generalized many known differential operators. The new q-operator and the concept of subordination were afterwards, used to define a new subclass of analytic-univalent functions that invariably consists of several known and new generalizations of starlike functions. Consequently, some geometric properties of the new class were investigated. The properties include coefficient inequality, growth, distortion and covering properties. In fact, we solved some radii problems for the class and also established its subordinating factor sequence property. Indeed, varying some of the involving parameters in our results led to some existing results. [ABSTRACT FROM AUTHOR]

In this paper, we propose a two-level block preconditioned Jacobi--Davidson (BPJD) method for efficiently solving discrete eigenvalue problems resulting from finite element approximations of 2mth (m= 1, 2) order symmetric elliptic eigenvalue problems. Our method works effectively to compute the first several eigenpairs, including both multiple and clustered eigenvalues with corresponding eigenfunctions, particularly. The method is highly parallelizable by constructing a new and efficient preconditioner using an overlapping domain decomposition (DD). It only requires computing a couple of small scale parallel subproblems and a quite small scale eigenvalue problem per iteration. Our theoretical analysis reveals that the convergence rate of the method is bounded by c(H)(1 C\delta 2m 1 H2m 1)2, where H is the diameter of subdomains and\delta is the overlapping size among subdomains. The constant C is independent of the mesh size h and the internal gaps among the target eigenvalues, demonstrating that our method is optimal and cluster robust. Meanwhile, the H-dependent constant c(H) decreases monotonically to 1, as H\rightarrow 0, which means that more subdomains lead to the better convergence rate. Numerical results supporting our theory are given. [ABSTRACT FROM AUTHOR]

A numerical method for coupled 3D-1D problems with discontinuous solutions at the interfaces is derived and discussed. This extends a previous work on the subject where only continuous solutions were considered. Thanks to properly defined function spaces a well posed 3D-1D problem is obtained from the original fully 3D problem and the solution is then found by a PDE-constrained optimization reformulation. This is a domain decomposition strategy in which unknown interface variables are introduced and a suitably defined cost functional, expressing the error in fulfilling interface conditions, is minimized constrained by the constitutive equations on the subdomains. The resulting discrete problem is robust with respect to geometrical complexity thanks to the use of independent discretizations on the various subdomains. Meshes of different sizes can be used without affecting the conditioning of the discrete linear system, and this is a peculiar aspect of the considered formulation. An efficient solving strategy is further proposed, based on the use of a gradient based solver and yielding a method ready for parallel implementation. A numerical experiment on a problem with known analytical solution shows the accuracy of the method, and two examples on more complex configurations are proposed to address the applicability of the approach to practical problems. [ABSTRACT FROM AUTHOR]

The Hankel determinant H 2 , 1 F f - 1 / 2 of logarithmic coefficients is defined as H 2 , 1 F f - 1 / 2 : = Γ 1 Γ 2 Γ 2 Γ 3 = Γ 1 Γ 3 - Γ 2 2 , where Γ 1 , Γ 2 , and Γ 3 are the first, second, and third logarithmic coefficients of inverse functions belonging to the class S of normalized univalent functions. In this paper, we establish sharp inequalities H 2 , 1 F f - 1 / 2 ≤ 19 / 288 , H 2 , 1 F f - 1 / 2 ≤ 1 / 144 , and H 2 , 1 F f - 1 / 2 ≤ 1 / 36 for the logarithmic coefficients of inverse functions, considering starlike and convex functions, as well as functions with bounded turning of order 1/2, respectively. [ABSTRACT FROM AUTHOR]

In this paper, some local and parallel finite element methods based on two-grid discretizations are provided and studied for the non-stationary Stokes-Darcy model with the Beavers-Joseph interface condition. Two local algorithms, the semi-discrete and fully discrete finite element algorithms, are first introduced and related error estimates are rigorously derived. Based upon the fully discrete local algorithm, two fully discrete parallel algorithms are subsequently developed. The backward Euler scheme is considered for the temporal discretization and finite element method is used for the spatial discretization. The main idea of the parallel algorithms is to solve a decoupled Stokes-Darcy model via a coarse grid on the whole domain, then solve residual equations with a finer grid on overlapped subdomains by some local and parallel procedures at each time step. Some local a priori error is also provided that is crucial to our theoretical analysis. Finally, some numerical results are reported to illustrate the validity of the algorithms. [ABSTRACT FROM AUTHOR]

In this paper, we propose and present a non-overlapping substructuring-type iterative algorithm for the Cahn–Hilliard (CH) equation, which is a prototype for phase-field models. It is of great importance to develop efficient numerical methods for the CH equation, given the range of applicability of CH equation has. Here we present a formulation for the linear and non-linear Dirichlet–Neumann (DN) methods applied to the CH equation and study the convergence behaviour in one and two spatial dimensions in multiple subdomains. We show numerical experiments to illustrate our theoretical findings and effectiveness of the method. [ABSTRACT FROM AUTHOR]

Making use of Ruscheweyh derivative, we dene a new class of starlike functions of complex order subordinate to a conic domain impacted by Janowski functions. Coecient estimates and Fekete-Szego inequalities for the dened class are our main results. Some of our results generalize the related work of some authors. [ABSTRACT FROM AUTHOR]

In this paper, we defined a new family of meromorphic functions whose analytic characterization was motivated by the definition of the multiplicative derivative. Replacing the ordinary derivative with a multiplicative derivative in the subclass of starlike meromorphic functions made the class redundant; thus, major deviation or adaptation was required in defining a class of meromorphic functions influenced by the multiplicative derivative. In addition, we redefined the subclass of meromorphic functions analogous to the class of the functions with respect to symmetric points. Initial coefficient estimates and Fekete–Szegö inequalities were obtained for the defined function classes. Some examples along with graphs have been used to establish the inclusion and closure properties.

The main purpose of this work is to study the third Hankel determinant for classes of Bernoulli lemniscate-related functions by introducing new subclasses of star-like functions represented by SLλ* and RLλ. In many geometric and physical applications of complex analysis, estimating sharp bounds for problems involving the coefficients of univalent functions is very important because these coefficients describe the fundamental properties of conformal maps. In the present study, we defined sharp bounds for function-coefficient problems belonging to the family of SLλ* and RLλ. Most of the computed bounds are sharp. This study will encourage further research on the sharp bounds of analytical functions related to new image domains.

The balancing domain decomposition by constraints (BDDC) methods are applied to the linear system arising from the hybridizable discontinuous Galerkin (HDG) discretization of the Oseen equation of incompressible flow. The generalized minimal residual method (GMRES) is used to accelerate the convergence. The original system is first reduced to a subdomain interface problem that is asymmetric indefinite, but can be positive definite in a special subspace. Edge/face average constraints can ensure all BDDC-preconditioned GMRES iterates stay in this special subspace. The convergence of the algorithm is analyzed, and additional edge/face constraints are used to improve the convergence. If the subdomain size is small enough, the number of iterations is independent of the number of subdomains, and depends only slightly on the subdomain problem size when the viscosity is large. When the viscosity is small, the convergence deteriorates. However, the numerical examples can give satisfactory results for the linear HDG discretization even with a small viscosity. [ABSTRACT FROM AUTHOR]

In this paper, we propose a two-level additive Schwarz preconditioner for the Nitsche extended finite element discretization of elliptic interface problems. The intergrid transfer operators between the coarse mesh and the fine mesh spaces are constructed and a stable space decomposition is given. It is proved that the condition number of the preconditioned system is bounded by C (1 + H δ + H h) , where H and h respectively stand for the coarse and fine mesh sizes, and δ measures the size of the overlaps between subdomains. The constant C does not depend on the contrast of the coefficients, how the interface intersects with the meshes. Numerical experiments are carried out to validate theoretical results. [ABSTRACT FROM AUTHOR]

A study of an alternating Schwarz domain decomposition method for a time evolution Rayleigh-Bénard problem is presented. The model equations are Navier-Stokes, continuity and heat equations in the case of infinite Prandtl number in a two-dimensional rectangular domain. The nonlinear evolution problem is dealt with an order two finite differences scheme in time and a collocation method in space. Each step in the evolution problem is solved with a Schwarz domain decomposition method. The domain is split into several subdomains with appropriate interface conditions. Their convergence properties are studied theoretically in a simplified domain divided in two subdomains. The convergence rate is less than one when an overlap is considered. The numerical resolution of the problem confirms the theoretical results. The number of subdomains in the horizontal direction can be increased indefinitely. A benchmark with numerical solutions obtained with other methods validates the method. Convergence is achieved for large spatial grids in the x axis, which are inabordable for the standard Legendre collocation method. Other advantage of this methodology is parallelization. [ABSTRACT FROM AUTHOR]

Over the last few years, Geometric Function Theory (GFT) as one of the most prime branch of complex analysis has gained a considerable and an impressive attention from many researchers, largely because it deals with the study of the geometric properties of analytic functions and their numerous applications in various fields of mathematics such as in special functions, probability distributions, and fractional calculus. The investigations in this paper are on two new classes of analytic functions defined in the unit disk ε = {z ∈ C : |z| < 1} and denoted by XSq (b,K) and XTq (b,K). Function f in the classes satisfy the conditions f(0) = f ′(0) -- 1 = 0, hence can be of series type f(z) = z + a2z² + a3z³ + …, z ∈ ε. The definition of the two new classes of analytic functions embed some well-known special functions such as the Galuê-type Struve function, modified error function and a starlike function whose coefficients are Bell's numbers while some involving mathematical principles are the q-derivative, inequalities, convolution and subordination. The main results from these classes are however, the upper estimates of some initial bounds such as |an| (n = 2, 3, 4) and the Fekete-Szegö functional |a3 - øa2/2| (ø ∈ C) of functions f ∈ XSq (b,K) and f ∈ XTq (b,K). [ABSTRACT FROM AUTHOR]

The implementation of discontinuous functions occurs in many of today's state-of-the-art partial differential equation solvers. However, in finite element methods, this poses an inherent difficulty: efficient quadrature rules available when integrating functions whose discontinuity falls in the element's interior are for low order degree polynomials, not easily extended to higher order degree polynomials, and cover a restricted set of geometries. Many approaches to this issue have been developed in recent years. Among them, one of the most elegant and versatile is the equivalent polynomial technique. This method replaces the discontinuous function with a polynomial, allowing integration to occur over the entire domain rather than integrating over complex subdomains. Although eliminating the issues involved with discontinuous function integration, the equivalent polynomial tactic introduces its problems. The exact subdomain integration requires a machinery that quickly grows in complexity when increasing the polynomial degree and the geometry dimension, restricting its applicability to lower order degree finite element families. The current work eliminates this issue. We provide algebraic expressions to exactly evaluate the subdomain integral of any degree polynomial on parent finite element shapes cut by a planar interface. These formulas also apply to the exact evaluation of the embedded interface integral. We provide recursive algorithms that avoid overflow in computer arithmetic for standard finite element geometries: triangle, square, cube, tetrahedron, and prism, along with a hypercube of arbitrary dimensions. [ABSTRACT FROM AUTHOR]

In this paper, by using the principal of subordination, we obtain sharp bounds for certain class of non-Bazilevič functions involving linear operator. [ABSTRACT FROM AUTHOR]

New exact solutions are presented to the problem of steadily travelling water waves with vorticity wherein a submerged von Kármán point vortex street cotravels with a wave on a linear shear current. Surface tension and gravity are ignored. The work generalizes an earlier study by Crowdy & Nelson (Phys. Fluids , vol. 22, 2010, 096601) who found analytical solutions for a single point vortex row cotravelling with a water wave in a linear shear current. The main theoretical tool is the Schwarz function of the wave, and the work builds on a novel framework set out recently by Crowdy (J. Fluid Mech. , vol. 954, 2022, A47). Conformal mapping theory is used to construct Schwarz functions with the requisite properties and to parametrize the waveform. A two-parameter family of solutions is found by solving a pair of nonlinear algebraic equations. This system of equations has intriguing properties: indeed, it is degenerate, which radically reduces the number of possible solutions, although the space of physically admissible equilibria is still found to be rich and diverse. For inline vortex streets, where the two vortex rows are aligned vertically, there is generally a single physically admissible solution. However, for staggered streets, where the two vortex rows are offset horizontally, certain parameter regimes produce multiple solutions. An important outcome of the work is that while only degenerate von Kármán point vortex streets can exist in an unbounded simple shear current, a broad array of such equilibria is possible in a shear current beneath a cotravelling wave on a free surface. [ABSTRACT FROM AUTHOR]

We study a new technique for reducing the number of iterations of the block Cimmino method by replicating rows in the partitioned system, so that we obtain a nondisjoint partitioning of the rows. Since rows in different partitions that are close to colinear produce a poorly conditioned iteration matrix for the block Cimmino method, row replication can get around this problem. With intelligent replication choices, we can reduce the number of iterations for convergence of the replicated block Cimmino method. The downside is a slight increase of the computational workload associated with each partition. In order to find a trade-off between a lower number of iterations and a higher cost per iteration, selecting the proper set of rows for replication is crucial. In this paper, we use graph-based techniques to find good candidates for replication. Since the block Cimmino method can be interpreted as a nonoverlapping additive Schwartz method applied to the normal equations, the replication techniques correspond to introducing an overlap between the subdomains defined by the partitions. We show analytically in the case of a two-block partitioning how the replication improves the condition number of the block Cimmino iteration matrix. We then use challenging two-dimensional PDE problems to show that our algebraic approach targets physically meaningful phenomena on the interface between partitions. We demonstrate the efficiency of the proposed method in improving the performance of the block Cimmino solver, even with a small amount of replication, on problems from the SuiteSparse Matrix Collection. Finally, we compare our approach to a BiCGStab preconditioned with an additive Schwartz method and show that our replication technique can be used to define the subdomains and overlaps in the context of domain decomposition methods. [ABSTRACT FROM AUTHOR]

Generalized eigenvalue problems on the overlap(GenEO) is a method for computing an operator-dependent spectral coarse space to be combined with local solves on subdomains to form a robust parallel domain decomposition preconditioner for elliptic PDEs. It has previously been proved, in the self-adjoint and positive-definite case, that this method, when used as a preconditioner for conjugate gradients, yields iteration numbers that are completely independent of the heterogeneity of the coefficient field of the partial differential operator. We extend this theory to the case of convection–diffusion–reaction problems, which may be nonself-adjoint and indefinite, and whose discretizations are solved with preconditioned GMRES. The GenEO coarse space is defined here using a generalized eigenvalue problem based on a self-adjoint and positive-definite subproblem. We prove estimates on GMRES iteration counts that are independent of the variation of the coefficient of the diffusion term in the operator and depend only very mildly on variations of the other coefficients. These are proved under the assumption that the subdomain diameter is sufficiently small and the eigenvalue tolerance for building the coarse space is sufficiently large. While the iteration number estimates do grow as the nonself-adjointness and indefiniteness of the operator increases, practical tests indicate the deterioration is much milder. Thus, we obtain an iterative solver that is efficient in parallel and very effective for a wide range of convection–diffusion–reaction problems. [ABSTRACT FROM AUTHOR]

L e t N be the class of functions that convex in one direction and M denote the class of functions z f ′ (z) , where f ∈ N . In the paper, the third-order Hankel determinants for these classes are estimated. The estimates of H 3 , 1 (f) obtained in the paper are improved. [ABSTRACT FROM AUTHOR]

The pre-Schwarzianand Schwarzian derivatives of analytic functions f are defined in U , where U is the open unit disk. The pre-Schwarzian as well as Schwarzian derivatives are popular tools for studying the geometric properties of analytic mappings. These can also be used to obtain either necessary or sufficient conditions for the univalence of a function f. Because of the computational difficulty, the pre-Schwarzian norm has received more attention than the Schwarzian norm. It has applications in the theory of hypergeometric functions, conformal mappings, Teichmüller spaces, and univalent functions. In this paper, we find sharp norm estimates of the pre-Schwarzian derivatives of certain subfamilies of analytic functions involving some conic-like image domains. These results may also be extended to the families of strongly starlike, convex, as well as to functions with symmetric and conjugate symmetric points. [ABSTRACT FROM AUTHOR]

We construct an overlapping additive Schwarz preconditioner for the biharmonic Dirichlet problems discretized by isogeometric analysis based on generalized B-splines (GB-splines) and analyze its optimal convergence rate bound that is cubic in the ratio between subdomains and overlap sizes. Our analysis is validated through a set of numerical experiments that illustrate good behavior of the proposed preconditioner with respect to the model parameters. [ABSTRACT FROM AUTHOR]

Highly heterogeneous, anisotropic coefficients, e.g., in the simulation of carbon-Fiber composite components, can lead to extremely challenging finite element systems. Direct solvers for the resulting large and sparse linear systems suffer from severe memory requirements and limited parallel scalability, while iterative solvers in general lack robustness. Two-level spectral domain decomposition methods can provide such robustness for symmetric positive definite linear systems by using coarse spaces based on independent generalized eigenproblems in the subdomains. Rigorous condition number bounds are independent of mesh size, number of subdomains, and coefficient contrast. However, their parallel scalability is still limited by the fact that (in order to guarantee robustness) the coarse problem is solved via a direct method. In this paper, we introduce a multilevel variant in the context of subspace correction methods and provide a general convergence theory for its robust convergence for abstract, elliptic variational problems. Assumptions of the theory are verified for conforming as well as for discontinuous Galerkin methods applied to a scalar diffusion problem. Numerical results illustrate the performance of the method for two- and three-dimensional problems and for various discretization schemes, in the context of scalar diffusion and linear elasticity. [ABSTRACT FROM AUTHOR]

This article comprises the study of strongly starlike functions which are defined by using the concept of subordination. The function φ defined by φ (ζ) = (1 + ζ) λ , 0 < λ < 1 maps the open unit disk in the complex plane to a domain symmetric with respect to the real axis in the right-half plane. Using this mapping, we obtain some radius results for a family of starlike functions. It is worth noting that all the presented results are sharp. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the sharp bounds of the second Hankel determinant of Logarithmic coefficients for the starlike and convex functions with respect to symmetric points in the open unit disk. [ABSTRACT FROM AUTHOR]

Optimized transmission conditions in domain decomposition methods have been the focus of intensive research efforts over the past decade. Traditionally, transmission conditions are optimized for two subdomains model configurations, and then used in practice for many subdomains. We optimizetransmission conditions here for the first time directly for many subdomains for a class of complex diffusion problems. Our asymptotic analysis leads to closed form optimized transmission conditions for many subdomains, and shows that the asymptotic best choice in the mesh size only differs from the two subdomain best choice in the constants, for which we derive the dependence on the number of subdomains explicitly, including the limiting case of an infinite number of subdomains, leading to new insight into scalability. Our results include both Robin and Ventcell transmission conditions, and we also optimize for the first time a two-sided Ventcell condition. We illustrate our results with numerical experiments, both for situations covered by our analysis and situations that go beyond. [ABSTRACT FROM AUTHOR]

The overlap function, a particular kind of binary aggregate function, has been extensively utilized in decision-making, image manipulation, classification, and other fields. With regard to overlap function theory, many scholars have also obtained many achievements, such as pseudo-overlap function, quasi-overlap function, semi-overlap function, etc. The above generalized overlap functions contain commutativity and continuity, which makes them have some limitations in practical applications. In this essay, we give the definition of pseudo-quasi overlap functions by removing the commutativity and continuity of overlap functions, and analyze the relationship of pseudo-t-norms and pseudo-quasi overlap functions. Moreover, we present a structure method for pseudo-quasi overlap functions. Then, we extend additive generators to pseudo-quasi overlap functions, and we discuss additive generators of pseudo-quasi overlap functions. The results show that, compared with the additive generators generated by overlap functions, the additive generators generated by pseudo-quasi overlap functions have fewer restraint conditions. In addition, we also provide a method for creating quasi-overlap functions by utilizing pseudo-t-norms and pseudo automorphisms. Finally, we introduce the idea of left-continuous pseudo-quasi overlap functions, and we study fuzzy inference triple I methods of residual implication operators induced by left-continuous pseudo-quasi overlap functions. On the basis of the above, we give solutions of pseudo-quasi overlap function fuzzy inference triple I methods based on FMP (fuzzy modus ponens) and FMT (fuzzy modus tollens) problems. [ABSTRACT FROM AUTHOR]

We study one variable meromorphic functions mapping a planar real algebraic set A to another real algebraic set in the complex plane. By using the theory of Schwarz reflection functions, we show that for certain A, these meromorphic functions must be rational. In particular, when A is the standard unit circle, we obtain a one dimensional analog of Poincaré [Acta Math. 2 (1883), pp. 97–113], Tanaka [J. Math. Soc. Japan 14 (1962), pp. 397–429] and Alexander's [Math. Ann. 209 (1974), pp. 249–256] rationality results for 2m-1 dimensional sphere in \mathbb {C}^m when m\ge 2. [ABSTRACT FROM AUTHOR]

In this paper, we prove a Schwarz lemma for the pentablock. The pentablock P is defined by P = { (a 21 , tr A , det A) : A = [ a ij ] i , j = 1 2 ∈ B 2 × 2 } where B 2 × 2 denotes the open unit ball in the space of 2 × 2 complex matrices. The pentablock is a bounded non-convex domain in C 3 which arises naturally in connection with a certain problem of μ -synthesis. We develop a concrete structure theory for the rational maps from the unit disc D to the closed pentablock P ¯ that map the unit circle T to the distinguished boundary b P ¯ of P ¯ . Such maps are called rational P ¯ -inner functions. We give relations between P ¯ -inner functions and inner functions from D to the symmetrized bidisc. We describe the construction of rational P ¯ -inner functions x = (a , s , p) : D → P ¯ of prescribed degree from the zeroes of a, s and s 2 - 4 p . The proof of this theorem is constructive: it gives an algorithm for the construction of a family of such functions x subject to the computation of Fejér–Riesz factorizations of certain non-negative trigonometric functions on the circle. We use properties and the construction of rational P ¯ -inner functions to prove a Schwarz lemma for the pentablock. [ABSTRACT FROM AUTHOR]

The generalized Schwarz algorithm for a class of elliptic quasi-variational inequalities related to impulse control problems is studied in this paper. The principal result is to prove the error estimate in L ∞ -norm for m subdomains with overlapping nonmatching grids. This approach combines the geometrical convergence and the uniform convergence. [ABSTRACT FROM AUTHOR]

In this paper, we consider the Newton-Schur method in Hilbert space and obtain quadratic convergence. For the symmetric elliptic eigenvalue problem discretized by the standard finite element method and nonoverlapping domain decomposition method, we use the Steklov-Poincaré operator to reduce the eigenvalue problem on the domain Ω into the nonlinear eigenvalue subproblem on Γ, which is the union of subdomain boundaries. We prove that the convergence rate for the Newton-Schur method is ∈N ≤ C∈7#178;, where the constant C is independent of the fine mesh size h and coarse mesh size H, and ∈N and ∈ are errors after and before one iteration step, respectively. For one specific inner product on Γ, a sharper convergence rate is obtained, and we can prove that ∈N ≤ C H²(1 + ln(H/h))²∈². Numerical experiments confirm our theoretical analysis. [ABSTRACT FROM AUTHOR]

In the present work, we establish the strong approximations of the empirical k-spacings process {αn(x): 0 ≤ x< ∞} (cf. (3)). We state the moment convergence rates results for this process. [ABSTRACT FROM AUTHOR]

In the present work, by using the concept of q-Ruscheweyh derivative, we define new subclasses of analytic functions of complex order with respect to (j, k)-symmetric points and we discuss the coefficient estimates for these defined classes. [ABSTRACT FROM AUTHOR]

In this paper, we present a hybrid algorithm based on parareal and Schwarz waveform relaxation (SWR) for solving time dependent partial differential equations. The parallelism can be simultaneously realized in the time direction by using a parareal and in the space direction via SWR. We give a convergence analysis for the hybrid algorithm for a 1D model problem, the reaction-diffusion equation. Weak scaling of the algorithm in terms of both the number of space subdomains and the number of paralleled time intervals were investigated via theoretical analysis and numerical experiments. [ABSTRACT FROM AUTHOR]

Abstract In this article, by employing the hyperbolic tangent function tanhz, a subfamily S tanh ∗ $\mathcal{S}_{\tanh }^{\ast }$ of starlike functions in the open unit disk D ⊂ C $\mathbb{D}\subset \mathbb{C}$ : D = { z : z ∈ C and | z | < 1 } $$\begin{aligned} \mathbb{D}= \bigl\{ z:z\in \mathbb{C} \text{ and } \vert z \vert < 1 \bigr\} \end{aligned}$$ is introduced and investigated. The main contribution of this article includes derivations of sharp inequalities involving the Taylor–Maclaurin coefficients for functions belonging to the class S tanh ∗ $\mathcal{S}_{\tanh }^{\ast } $ of starlike functions in D $\mathbb{D}$ . In particular, the bounds of the first three Taylor–Maclaurin coefficients, the estimates of the Fekete–Szegö type functionals, and the estimates of the second- and third-order Hankel determinants are the main problems that are proposed to be studied here.

A novel embedded domain decomposition method (EDDM) is proposed to simulate electromagnetic scattering from structures in an inhomogeneous medium. In this method, the inhomogeneous medium (e.g., layered substrate) is set as the background subdomain, and the integrated structures (e.g., metallic/dielectric components) with properly defined buffer regions (BRs) are set as the embedded subdomains, where the meshes of two can be completely independent and arbitrarily overlapping. The major contribution of this work lies in the following three aspects. First, to allow for arbitrary inclusion of the embedded subdomains in an inhomogeneous background subdomain, an adaptive BR method is developed. The self-coupling equation is rederived to ensure the consistency of the BR and the inhomogeneous background, and a new mutual-coupling equation is introduced to account for the material and/or conductor differences. Second, the boundary element method (BEM) accelerated by the multilevel fast multipole algorithm (MLFMA) is utilized to truncate the finite-element region so that the computation capability can be enhanced and the extra air box setting of the background subdomain in the original EDDM can be avoided. Third, for structure adjustments such as translations and rotations, we further propose an inherited calculation to avoid mesh regeneration and repeated computation of the self-coupling and preconditioning matrices and also reduce the iteration counts and solution time. Numerical examples have shown the accuracy, robustness, and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

The existence of an integral relation between self-induced velocity of a uniform, planar vortex and Schwarz function of its boundary opens the way to understand the kinematics of the vortex by analysing the internal singularities of that function. In general, they are branch cuts and form the so-called "mother body" of the vortex, because they generate the same external velocities of the vortex, by means of a relation identical to the Biot–Savart law for a vortex sheet. The jump of the Schwarz function across the cuts plays the role of the (complex) density of circulation. This paper investigates the singularities of polygonal vortices, which are highly nontrivial steady vortices widely present in Nature, and having fascinating properties, some of them still not well understood. By means of the equation of the dynamics of the Schwarz function specialised for steady vortices, a numerical tool based on elementary properties of the holomorphic functions is used for detecting the internal singularities and evaluating their strengths. In this way, it is shown that an nagonal vortex possesses n internal branch cuts. In a reference system having origin on the centre of vorticity of the vortex and real axis crossing one of its vertices, these cuts start from the origin and are directed along the n roots of the unity, so that they are aligned with the vertices. The positions of the branch points and the values assumed by the Schwarz function in these points are calculated by evaluating this function just outside the vortex boundary. Once the conditions on the branch points are defined, a power series representation of the Schwarz function is proposed, that is able to explain the behaviour of its real and imaginary parts in neighbourhoods of these points. Some conjectures about the external singularities are also discussed. [ABSTRACT FROM AUTHOR]

A new subclass of bi-close-to-convex functions associated with the generalized hypergeometric functions defined in ∆ = { z ∈ C : | z | < 1 } is introduced. The estimates for the general Taylor–Maclaurin coefficients of the functions in the introduced subclass are obtained by making use of Faber polynomial expansions. In particular, several previous results are generalized. [ABSTRACT FROM AUTHOR]