The Uniqueness Problem of Non-Gaussian Linear Processes

Consider a linear time series which is represented aswhere u_t is an independent and identically distributed random series with Eu_t=0,Eu_t~2=σ~2>0,w_t is a square-summable sequence     

Admissible Linear Estimation in Linear Models

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Convergence Rates of the Distributions of Error Variance Estimates in Linear Models

The best possible rate of convergence of the distributions of error variance estimates in linear models, based on the residual sum of squares, is obtained under weakest possible conditions.     

The Proof of a Theorem in DC Problem

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The Algebra of Estimation in Linear Econometric Systems∗

In econometrics it is common for variables to be related together in a set of linear, multilateral and causal interdependencies. This type of system generally has properties which are unsatisfactory for application of classical regression techniques. Consequently, alternative estimation methods have been developed. This paper explores the relations between several such methods in terms of symmetric idempotents of predetermined variables and their orthogonal complements. Generalizations of two‐ and three‐stage least squares and instrumental variables are considered, including Wicken's estimator.² The relative efficiencies of the estimators are also discussed.

     

The Degree of Unsolvability of Models

The purpose of this paper is to describe the complexity of models by theirdegrees of unsolvability,J.Richter defined the degree of a structure to be deg ()=sup{deg(),deg(R_i),i=1,…,n},Where is a model for afinite language L={R_i,i=1,…,n}and the universe of is a subset of ω. Shepointed out that, according to her definition, there can be models which areisomorphic but their degrees are different.Also,her discussions are restricted tofinite languages and models whose universes are subsets of ω.     

Truncated Estimator of Asymptotic Covariance Matrix in Partially Linear Models with Heteroscedastic Errors

A partially linear regression model with heteroscedastic and/or serially correlated errors is studied here. It is well known that in order to apply the semiparametric least squares estimation （SLSE） to make statistical inference a consistent estimator of the asymptotic covariance matrix is needed. The traditional residual-based estimator of the asymptotic covariance matrix is not consistent when the errors are heteroscedastic and/or serially correlated. In this paper we propose a new estimator by truncating, which is an extension of the procedure in White. This estimator is shown to be consistent when the truncating parameter converges to infinity with some rate.     

Asysmptotic Normality of the M－estimators for Parametric Components in Partly Linear Models

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On Rubel’s Problem in the Class of Linear Operators on the Space of Analytic Functions

In this paper, we describe all derivation pairs of linear operators that act in spaces of functions analytic in domains.     

Are You Convinced? Middle‐Grade Students' Evaluations of Mathematical Arguments

Students learn norms of proving by observing teachers generating proofs, engaging in proving, and generalizing features of proofs deemed convincing by an authority, such as a textbook. Students at all grade levels have difficulties generating valid proof; however, little research exists on students' understandings about what makes a mathematical argument convincing prior to more formal instruction in methods of proof. This study investigated middle‐school students' (ages 12–14) evaluations of arguments for a statement in number theory. Students evaluated both an empirical and a general argument in an interview setting. The results show that students tend to prefer empirical arguments because examples enhance an argument's power to show that the statement is true. However, interview responses also reveal that a significant number of students find arguments to be most convincing when examples are supported with an explanation that “tells why” the statement is true. The analysis also examined the alignment of students' reasons for choosing arguments as more convincing along with the strategies they employ to make arguments more convincing. Overall, the findings show middle‐school students' conceptions about what makes arguments convincing are more sophisticated than their performance in generating arguments suggests.     

The Representation of Continuous Linear Operator by Integral

LetXoverthefieldKstandforacompletelocallyconvexspace,andweassumethatitstopologyisgeneratedbyafamilyPofcontinuousseminormsonX,Let(O,Z,p)beafinitepositivemeasurespace.Afunctionf:Q-Xissaidtobep-integrable(forthedefinition,see[1]),ifthereexistsasequence{ft}ofsimplefunctionssuchthat.,ThislimitexistsandisinX.Denote,p)asthespaceofcIassesofNintegrablefunctionswhereLfj=Lgjifandonlyiff=gP-a.e..Putq(f)=j.p(f)dp,foreachpeP.ThetopologyonL1(p,Z)consideredisthese,generatedbyalltheq.L.EggheLlIhaspro…     

The Local Asymptotic Behavior of Solutions of Second Order Linear Differential Equations in a Nutshell

1.IntroductionGiven a second order linear differential equation with meromorphic coefficienta(x)y” b(x)y’ c(x)y=0 (1.1)in,a domain D the local analytic theory for such equations is well developed,see e.g.[8].If x_0 is a regular point for(1.1)then the theory advocates to utilize Taylor seriesexpansions of two linearly indepentdent solutions of(1.1).If x_0 is a regular singular pointfor(1.1),Frobenius’method tells us to follow sometimes a laborious procedure which     

The Theory of Finite Models without Equal Sign

In this paper, it is the first time ever to suggest that we study the model theory of all finite structures and to put the equal sign in the same situtation as the other relations. Using formulas of infinite lengths we obtain new theorems for the preservation of model extensions, submodels, model homomorphisms and inverse homomorphisms. These kinds of theorems were discussed in Chang and Keisler＇s Model Theory, systematically for general models, but Gurevich obtained some different theorems in this direction for finite models. In our paper the old theorems manage to survive in the finite model theory. There are some differences between into homomorphisms and onto homomorphisms in preservation theorems too. We also study reduced models and minimum models. The characterization sentence of a model is given, which derives a general result for any theory T to be equivalent to a set of existential-universal sentences. Some results about completeness and model completeness are also given.     

The Newton–Wigner Problem in the Relativistic Quantum Mechanics of Free Particles

We discuss the old Newton–Wigner problem, which is understood as the problem of a correct coordinate interpretation of the relativistic quantum mechanics of free particles. This problem is still relevant for quantum field theory because the S-matrix approach assumes that asymptotic fields describe relativistic free quantum-mechanical particles. From the modern standpoint, the original solution of this problem by Newton and Wigner already cannot be considered sufficient because it admits the smearing of wave packets with a superlight velocity. We discuss a possibility of overcoming this difficulty. This possibility is connected with relativistic deformations of the standard Heisenberg algebra. We describe situations in which a sort of desingularization of the effective free Hamiltonian occurs for some special deformations, which possibly allows preserving sublight velocity in the theory.     

The Cauchy Problem of a Shallow Water Equation

We consider the Cauchy problem of a shallow water equation and its local wellposedness.     

The Cauchy Problem of the Nonlinear Schrodinger Equations in R^1＋1

In this paper, we consider the local and global solution for the nonlinear Schrodinger equation with data in the homogeneous and nonhomogeneous Besov space and the scattering result for small data. The techniques to be used are adapted from the Strichartz type estimate, Kato＇s smoothing effect and the maximal function （in time） estimate for the free SchrSdinger operator.     

The Problem of Finding the Kernels in the System of Integro-Differential Maxwell’s Equations

Journal of Applied and Industrial Mathematics - We pose the direct and inverse problems of finding the electromagnetic field and the diagonal memory matrix for the reduced canonical system of...     

A Note on the Optimality of Generalized Cross-validation Bandwidth Selection in Partially Linear Models with Kernel Smoothing Estimator

The issue of selection of bandwidth in kernel smoothing method is considered within the context of partially linear models, hi this paper, we study the asymptotic behavior of the bandwidth choice based on generalized cross-validation （CCV） approach and prove that this bandwidth choice is asymptotically optimal. Numerical simulation are also conducted to investigate the empirical performance of generalized cross-valldation.