Inequalities for the Hurwitz zeta function

2000 ◽  
Vol 130 (6) ◽  
pp. 1227-1236 ◽  
Author(s):  
Horst Alzer
Keyword(s):  
Zeta Function ◽  
Hurwitz Zeta Function ◽  
Real Numbers ◽  
Positive Real ◽  
Image Position

Let be the Hurwitz zeta function. Furthermore, let p > 1 and α ≠ 0 be real numbers and n ≥ 2 be an integer. We determine the best possible constants a(p, α, n), A(p, α, n), b(p, n) and B(p, n) such that the inequalities and hold for all positive real numbers x1,…,xn.

Monotonicity Properties of the Hurwitz Zeta Function

2005 ◽  
Vol 48 (3) ◽  
pp. 333-339 ◽  
Author(s):  
Horst Alzer
Keyword(s):  
Zeta Function ◽  
Hurwitz Zeta Function ◽  
Real Numbers ◽  
Monotonicity Properties ◽  
Image Position

AbstractLetbe the Hurwitz zeta function and letwhereα, β> 1 anda,b> 0 are real numbers. We prove: (i) The functionQis decreasing on (0, ∞) iffαa−βb≥ max(a−b, 0). (ii)Qis increasing on (0, ∞) iffαa−βb≤ min(a−b, 0). An application of part (i) reveals that for allx> 0 the functions⟼ [(s− 1)ζ(s,x)]1/(s−1)is decreasing on (1, ∞). This settles a conjecture of Bastien and Rogalski.

scholarly journals Three proofs of Minkowski's second inequality in the geometry of numbers

1965 ◽  
Vol 5 (4) ◽  
pp. 453-462 ◽  
Author(s):  
R. P. Bambah ◽  
Alan Woods ◽  
Hans Zassenhaus
Keyword(s):  
Convex Set ◽  
Geometry Of Numbers ◽  
Real Numbers ◽  
Open Convex ◽  
Positive Real ◽  
Original Proof ◽  
Linearly Independent ◽  
Image Position

Let K be a bounded, open convex set in euclidean n-space Rn, symmetric in the origin 0. Further let L be a lattice in Rn containing 0 and put extended over all positive real numbers ui for which uiK contains i linearly independent points of L. Denote the Jordan content of K by V(K) and the determinant of L by d(L). Minkowski's second inequality in the geometry of numbers states that Minkowski's original proof has been simplified by Weyl [6] and Cassels [7] and a different proof hasbeen given by Davenport [1].

scholarly journals A Cyclic Inequality and an Extension of it. II

1962 ◽  
Vol 13 (2) ◽  
pp. 143-152 ◽  
Author(s):  
P. H. Diananda
Keyword(s):  
Real Numbers ◽  
Positive Real ◽  
Cyclic Inequality ◽  
Image Position ◽  
Positive Integers

Throughout this paper, unless otherwise stated, n and L stand for positive integers and α, t, x, x1, x2, … for positive real numbers. Letwhereand

Eigenvalues of positive integral operators with certain entire kernels

1986 ◽  
Vol 99 (3) ◽  
pp. 535-545 ◽  
Author(s):  
G. Little
Keyword(s):  
Integral Operator ◽  
Integral Operators ◽  
Real Numbers ◽  
Positive Real ◽  
Summable Sequence ◽  
Strictly Positive Real ◽  
Image Position

Suppose that (an) (n ≥ 0) is a square-summable sequence of strictly positive real numbers; then the integral operator T on L2(− 1,1) given byis compact and positive and, therefore, its eigenvalues can be arranged into a sequence λ0 ≥ λ1 ≥ λ2 ≥ … of non-negative real numbers which decreases to 0.

scholarly journals Oscillation of differential equations with non-monotone retarded arguments

2016 ◽  
Vol 19 (1) ◽  
pp. 98-104 ◽  
Author(s):  
George E. Chatzarakis ◽  
Özkan Öcalan
Keyword(s):  
Differential Equation ◽  
Differential Equations ◽  
Oscillation Criterion ◽  
Retarded Argument ◽  
Real Numbers ◽  
Positive Real ◽  
First Order ◽  
Retarded Differential Equation ◽  
Oscillation Condition ◽  
Image Position

Consider the first-order retarded differential equation $$\begin{eqnarray}x^{\prime }(t)+p(t)x({\it\tau}(t))=0,\quad t\geqslant t_{0},\end{eqnarray}$$ where $p(t)\geqslant 0$ and ${\it\tau}(t)$ is a function of positive real numbers such that ${\it\tau}(t)\leqslant t$ for $t\geqslant t_{0}$, and $\lim _{t\rightarrow \infty }{\it\tau}(t)=\infty$. Under the assumption that the retarded argument is non-monotone, a new oscillation criterion, involving $\liminf$, is established when the well-known oscillation condition $$\begin{eqnarray}\liminf _{t\rightarrow \infty }\int _{{\it\tau}(t)}^{t}p(s)\,ds>\frac{1}{e}\end{eqnarray}$$ is not satisfied. An example illustrating the result is also given.

scholarly journals Averaging distances in certain Banach spaces

1997 ◽  
Vol 55 (1) ◽  
pp. 147-160 ◽  
Author(s):  
Reinhard Wolf
Keyword(s):  
Banach Space ◽  
Hausdorff Space ◽  
Finite Dimension ◽  
Closed Interval ◽  
Continuous Functions ◽  
Real Numbers ◽  
Empty Interval ◽  
Positive Real ◽  
Complete Discussion ◽  
Image Position

Let E be a Banach space. The averaging interval AI(E) is defined as the set of positive real numbers α, with the following property: For each n ∈ ℕ and for all (not necessarily distinct) x1, x2, … xn ∈ E with ∥x1∥ = ∥x2∥ = … = ∥xn∥ = 1, there is an x ∈ E, ∥x∥ = 1, such thatIt follows immediately, that AI(E) is a (perhaps empty) interval included in the closed interval [1,2]. For example in this paper it is shown that AI(E) = {α} for some 1 < α < 2, if E has finite dimension. Furthermore a complete discussion of AI(C(X)) is given, where C(X) denotes the Banach space of real valued continuous functions on a compact Hausdorff space X. Also a Banach space E is found, such that AI(E) = [1,2].

HEAT KERNEL METHOD FOR THE LEVI-CIVITÁ EQUATION IN DISTRIBUTIONS AND HYPERFUNCTIONS

2015 ◽  
Vol 92 (1) ◽  
pp. 77-93
Author(s):  
JAEYOUNG CHUNG ◽  
PRASANNA K. SAHOO
Keyword(s):  
Functional Equation ◽  
Stability Problem ◽  
Kernel Method ◽  
Functional Inequality ◽  
Complex Numbers ◽  
Ulam Stability ◽  
Real Numbers ◽  
Positive Real ◽  
Image Position ◽  
Ulam Stability Problem

Let$G$be a commutative group and$\mathbb{C}$the field of complex numbers,$\mathbb{R}^{+}$the set of positive real numbers and$f,g,h,k:G\times \mathbb{R}^{+}\rightarrow \mathbb{C}$. In this paper, we first consider the Levi-Civitá functional inequality$$\begin{eqnarray}\displaystyle |f(x+y,t+s)-g(x,t)h(y,s)-k(y,s)|\leq {\rm\Phi}(t,s),\quad x,y\in G,t,s>0, & & \displaystyle \nonumber\end{eqnarray}$$where${\rm\Phi}:\mathbb{R}^{+}\times \mathbb{R}^{+}\rightarrow \mathbb{R}^{+}$is a symmetric decreasing function in the sense that${\rm\Phi}(t_{2},s_{2})\leq {\rm\Phi}(t_{1},s_{1})$for all$0<t_{1}\leq t_{2}$and$0<s_{1}\leq s_{2}$. As an application, we solve the Hyers–Ulam stability problem of the Levi-Civitá functional equation$$\begin{eqnarray}\displaystyle u\circ S-v\otimes w-k\circ {\rm\Pi}\in {\mathcal{D}}_{L^{\infty }}^{\prime }(\mathbb{R}^{2n})\quad [\text{respectively}\;{\mathcal{A}}_{L^{\infty }}^{\prime }(\mathbb{R}^{2n})] & & \displaystyle \nonumber\end{eqnarray}$$in the space of Gelfand hyperfunctions, where$u,v,w,k$are Gelfand hyperfunctions,$S(x,y)=x+y,{\rm\Pi}(x,y)=y,x,y\in \mathbb{R}^{n}$, and$\circ$,$\otimes$,${\mathcal{D}}_{L^{\infty }}^{\prime }(\mathbb{R}^{2n})$and${\mathcal{A}}_{L^{\infty }}^{\prime }(\mathbb{R}^{2n})$denote pullback, tensor product and the spaces of bounded distributions and bounded hyperfunctions, respectively.

Summability fields which span the bounded sequences

1967 ◽  
Vol 63 (1) ◽  
pp. 99-106 ◽  
Author(s):  
J. W. Baker ◽  
G. M. Petersen
Keyword(s):  
Regular Matrix ◽  
Real Numbers ◽  
Positive Real ◽  
Finite Set ◽  
Image Position ◽  
Bounded Sequences

If A = (am, n) is a regular matrix, then for any sequence x = {xn}, Am(x) will denote the transform and A-lim x denotes if that limit exists. We shall denote by the set of bounded sequences which are summed by A. If B is another regular matrix with then we say that B is b-stronger than A. In that case B must be b-consistent with A (see (4) and (6)), i.e. if thenIf {μn} is a sequence of positive real numbers with we say that A and B are (μn)-consistent if every sequencer x = {xn} satisfying xn = 0(μn) which is summed by both A and B is summed to the same value by both matrices. A finite set of matrices A1, A2, …, AN is said to be simultaneously (μn)-inconsistent (b-consistent) if whenever is summed by Ai with (i = l, 2, …, N) then implies that The set of sequences, is denoted by

On the inversion of Fourier transforms

1989 ◽  
Vol 40 (3) ◽  
pp. 429-439
Author(s):  
Nakhlé H. Asmar ◽  
Kent G. Merryfield
Keyword(s):  
Fourier Transforms ◽  
Locally Compact Abelian Group ◽  
Real Numbers ◽  
Positive Real ◽  
Locally Compact ◽  
Character Group ◽  
Almost Everywhere ◽  
Pointwise Limit ◽  
Compact Abelian Groups ◽  
Image Position

Let G be a locally compact abelian group, with character group Ĝ. Let ψ be an arbitrary continuous real-valued homomorphism defined on Ĝ. For f in LP(G), 1 < p ≤ 2, letwhere 1[−ν, ν] is the indicator function of the interval [ − ν, ν ], and I is an unbounded increasing sequence of positive real numbers. Then there is a constant Mp, independent of f, such that ‖M#f‖p ≤ Mp ‖f‖p. Consequently, the pointwise limit of the function exists, almost everywhere on G, as ν tends to infinity. Using this result and a generalised version of Riesz's theorem on conjugate functions, we obtain a pointwise inversion for Fourier transforms of functions on Ra × Tb, where a and b are nonnegative integers, and on various other locally compact abelian groups.

On a theorem of S. Bernstein

1952 ◽  
Vol 48 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Shih-Hsun Chang
Keyword(s):  
Entire Function ◽  
Real Numbers ◽  
Genus Zero ◽  
Positive Real ◽  
Image Position

S. Bernstein (see(l), pp. 198–204) has proved that ifis an entire function of genus zero, then the seriesis convergent. By considering the most unfavourable case, when all the (βn) are positive real numbers, and writingwhich is convergent by hypothesis, he proved that.

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