scholarly journals A local mean-value theorem for analytic functions with smooth boundary values

1974 ◽  
Vol 15 (1) ◽  
pp. 27-29 ◽  
Author(s):  
W. P. Novinger
Keyword(s):  
Analytic Function ◽  
Direct Consequence ◽  
Mean Value ◽  
Open Mapping ◽  
Mean Value Theorem ◽  
Open Mapping Theorem ◽  
Easy Consequence ◽  
Open Set ◽  
One To One ◽  
Image Position

Let f be an analytic function on a connected open set Ώ in the complex plane. Then, for given a, b ∈ Ώ, the equationneed not have a solution z ∈ Ώ. As a matter of fact, this would happen with each locally one-to-one analytic function which is not one-to-one on Ώ. But if we fix a a ∈ Ώ, then, for all b sufficiently close to a, (1) is solvable for z. This is an easy consequence of the Open Mapping Theorem applied to f'. For, assuming that f' is non-constant (otherwise, (1) holds for all a, b, z ∈Ώ), the Open Mapping Theorem tells us that f'(Ώ), the image under f' of Ώ, is an open neighbourhood of f'(a); so it is a direct consequence of the definition of f'(a) that there exists δ > 0 such that 0 < |b – a| < δ implies (f(b) – f(a))/(b – a) ∈f'(Ώ). A stronger statement has been obtained by J. M. Robertson [1, p. 329], who has shown thatand, if f''(a) ≠ 0, then.

scholarly journals A local mean value theorem for the complex plane

1969 ◽  
Vol 16 (4) ◽  
pp. 329-331 ◽  
Author(s):  
J. M. Robertson
Keyword(s):  
Complex Plane ◽  
Mean Value ◽  
Mean Value Theorem ◽  
Local Mean ◽  
Rouche’S Theorem ◽  
Image Position ◽  
Rouché's Theorem

The equationneed not have a solution z in the complex plane, even when ƒ is entire. For example, let ƒ(z) = ez, z1 = z0+2kπi. Thus the classical mean value theorem does not extend to the complex plane. McLeod has shown (2) that if ƒ is analytic on the segment joining z1 and z0, then there are points w1 and w2 on the segment such that where The purpose of this article is to give a local mean value theorem in the complex plane. We show that there is at least one point z satisfying (1), which we will call a mean value point, near z1 and z0 but not necessarily on the segment joining them, provided z1 and z0 are sufficiently close. The proof uses Rouché's Theorem (1).

The mean value theorem in second order arithmetic

2001 ◽  
Vol 66 (3) ◽  
pp. 1353-1358 ◽  
Author(s):  
Christopher S. Hardin ◽  
Daniel J. Velleman
Keyword(s):  
Mean Value ◽  
Second Order ◽  
Mean Value Theorem ◽  
Natural Numbers ◽  
Second Order Arithmetic ◽  
Elementary Analysis ◽  
Logical Connectives ◽  
The Mean ◽  
Order Arithmetic ◽  
Image Position

This paper is a contribution to the project of determining which set existence axioms are needed to prove various theorems of analysis. For more on this project and its history we refer the reader to [1] and [2].We work in a weak subsystem of second order arithmetic. The language of second order arithmetic includes the symbols 0, 1, =, <, +, ·, and ∈, together with number variables x, y, z, … (which are intended to stand for natural numbers), set variables X, Y, Z, … (which are intended to stand for sets of natural numbers), and the usual quantifiers (which can be applied to both kinds of variables) and logical connectives. We write ∀x < t φ and ∃x < t φ as abbreviations for ∀x(x < t → φ) and ∃x{x < t ∧ φ) respectively; these are called bounded quantifiers. A formula is said to be if it has no quantifiers applied to set variables, and all quantifiers applied to number variables are bounded. It is if it has the form ∃xθ and it is if it has the form ∀xθ, where in both cases θ is .The theory RCA0 has as axioms the usual Peano axioms, with the induction scheme restricted to formulas, and in addition the comprehension scheme, which consists of all formulas of the formwhere φ is , ψ is , and X does not occur free in φ(n). (“RCA” stands for “Recursive Comprehension Axiom.” The reason for the name is that the comprehension scheme is only strong enough to prove the existence of recursive sets.) It is known that this theory is strong enough to allow the development of many of the basic properties of the real numbers, but that certain theorems of elementary analysis are not provable in this theory. Most relevant for our purposes is the fact that it is impossible to prove in RCA0 that every continuous function on the closed interval [0, 1] attains maximum and minimum values (see [1]).Since the most common proof of the Mean Value Theorem makes use of this theorem, it might be thought that the Mean Value Theorem would also not be provable in RCA0. However, we show in this paper that the Mean Value Theorem can be proven in RCA0. All theorems stated in this paper are theorems of RCA0, and all of our reasoning will take place in RCA0.

scholarly journals Curves with zero derivative in F-spaces

1981 ◽  
Vol 22 (1) ◽  
pp. 19-29 ◽  
Author(s):  
N. J. Kalton
Keyword(s):  
Characteristic Function ◽  
Mean Value ◽  
Mean Value Theorem ◽  
Continuous Linear ◽  
Linear Functionals ◽  
Continuous Map ◽  
Left And Right ◽  
The Mean ◽  
Image Position ◽  
Locally Convex

Let X be an F-space (complete metric linear space) and suppose g:[0, 1] → X is a continuous map. Suppose that g has zero derivative on [0, 1], i.e.for 0≤t≤1 (we take the left and right derivatives at the end points). Then, if X is locally convex or even if it merely possesses a separating family of continuous linear functionals, we can conclude that g is constant by using the Mean Value Theorem. If however X* = {0} then it may happen that g is not constant; for example, let X = Lp(0, 1) (0≤p≤1) and g(t) = l[0,t] (0≤t≤1) (the characteristic function of [0, t]). This example is due to Rolewicz [6], [7; p. 116].

An open mapping theorem

1973 ◽  
Vol 74 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Kung-Fu Ng
Keyword(s):  
Vector Space ◽  
Topological Vector Space ◽  
A Priori ◽  
Open Mapping ◽  
Positive Real ◽  
Closed Linear Subspace ◽  
Open Mapping Theorem ◽  
Closed Cone ◽  
Image Position ◽  
Normed Vector

Let (E, τ) be a complete, semi-metrizable topological vector space. Let p be a pseudo-norm (not to be confused with a semi-norm, cf. (8), p. 18) inducing the topology τ. For each positive real number r, letLet f be a continuous linear function from E into a topological vector space F. The open mapping theorem of Banach may be stated as follows: If f is nearly open, that is, if the closure of each f(Vr) is a neighbourhood of O in F then whenever β > α > O; in particular, each f(Vr) is a neighbourhood of O. We note that f, identifying with its graph, is a closed linear subspace of the product space E × F. In this paper, we shall employ techniques developed by Kelley (6) and Baker (1) to extend the theorem to the case where f is taken to be a closed cone in E × F. The generalized theorem throws some light onto the duality theory of ordered spaces. In particular, the theorem of Andô–Ellis is generalized to (not assumed, a priori to be complete) normed vector spaces.

A simpler proof of Levinson's theorem

1985 ◽  
Vol 97 (3) ◽  
pp. 385-395 ◽  
Author(s):  
J. B. Conrey ◽  
A. Ghosh
Keyword(s):  
Functional Equation ◽  
Critical Line ◽  
Mean Value ◽  
Mean Value Theorem ◽  
Levinson’S Theorem ◽  
The Mean ◽  
Image Position

In this paper we present a proof of the mean-value theorem required by Levinson to show that at least one-third of the zeros of ζ(s) are on the critical line. As in Levinson [3], letwhere Χ(s)=ζ(s)/ζ(1−s) is the usual factor from the functional equation, and letwhereandwhere

Mean value theorem connected with Fourier coefficients of Hecke-Maass forms for SL(m, ℤ)

2016 ◽  
Vol 161 (2) ◽  
pp. 339-356 ◽  
Author(s):  
YUJIAO JIANG ◽  
GUANGSHI LÜ ◽  
XIAOFEI YAN
Keyword(s):  
Fourier Coefficients ◽  
Mean Value ◽  
Implied Constant ◽  
Symmetric Power ◽  
Mean Value Theorem ◽  
Maass Forms ◽  
Maass Form ◽  
Formula Group ◽  
Image Position

AbstractLet F(z) be a Hecke–Maass form for SL(m, ℤ) with m ⩽ 3, or be the symmetric power lift of a Hecke–Maass form for SL(2, ℤ) if m = 4, 5 and let AF(n, 1, . . ., 1) be the coefficients of L-function attached to F. We establish $$\sum_{q\leq Q}\max_{(a,q)=1}\max_{y\leq x}\left|\sum_{n\leq y \atop n\equiv a\bmod q}A_F(n,1, \dots, 1)\Lambda(n)\right| \ll x\log^{-A}x,$$ where Q = xϑ−ϵ with some ϑ > 0, the implied constant depends on F, A, ϵ.

A modified form of Siegel's mean-value theorem

1955 ◽  
Vol 51 (4) ◽  
pp. 565-576 ◽  
Author(s):  
A. M. Macbeath ◽  
C. A. Rogers
Keyword(s):  
Characteristic Function ◽  
Mean Value ◽  
Möbius Function ◽  
Mean Value Theorem ◽  
Star Body ◽  
Mobius Function ◽  
Whole Space ◽  
Three Stages ◽  
Image Position

The Minkowski–Hlawka theorem† asserts that, if S is any n-dimensional star body, with the origin o as centre, and with volume less than 2ζ(n), then there is a lattice of determinant 1 which has no point other than o in S. One of the methods used to prove this theorem splits up into three stages, (a) A function ρ(x) is considered, and it is shown that some suitably defined mean value of the sumtaken over a suitable set of lattices Λ of determinant 1, is equal, or approximately equal, to the integralover the whole space. (b) By taking ρ(x) to be equal, or approximately equal, towhere σ(x) is the characteristic function of S, and μ(r) is the Möbius function, it is shown that a corresponding mean value of the sumwhere Λ* is the set of primitive points of the lattice Λ, is equal, or approximately equal, to

The mean square of the Dedekind zeta function in quadratic number fields

1989 ◽  
Vol 106 (3) ◽  
pp. 403-417 ◽  
Author(s):  
Wolfgang Müller
Keyword(s):  
Zeta Function ◽  
Number Fields ◽  
Mean Value ◽  
Fourth Power ◽  
Mean Value Theorem ◽  
Mean Square ◽  
Quadratic Number ◽  
Dedekind Zeta Function ◽  
The Mean ◽  
Image Position

Let K be a quadratic number field with discriminant D. The aim of this paper is to study the mean square of the Dedekind zeta function ζK on the critical line, i.e.It was proved by Chandrasekharan and Narasimhan[1] that (1) is at most of order O(T(log T)2). As they noted at the end of their paper, it ‘would seem likely’ that (1) behaves asymptotically like a2T(log T)2, with some constant a2 depending on K. Applying a general mean value theorem for Dirichlet polynomials, one can actually proveThis may be done in just the same way as this general mean value theorem can be used to prove Ingham's classical result on the fourth power moment of the Riemann zeta function (cf. [3], chapter 5). In 1979 Heath-Brown [2] improved substantially on Ingham's result. Adapting his method to the above situation a much better result than (2) can be obtained. The following Theorem deals with a slightly more general situation. Note that ζK(s) = ζ(s)L(s, XD) where XD is a real primitive Dirichlet character modulo |D|. There is no additional difficulty in allowing x to be complex.

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