Inclusion statements for operator equations by a continuity principle

The paper is concerned with Range-Domain Implications MvCvK, where M is a given operator and C,K denote given sets. Sufficient conditions are derived by a very general continuity principle. Various special cases are considered such as inverse-positivity, MvMwvw, and a generalization H(,[,])MvH(,[,]) v, where Mu=H(u,u) and [,] denotes an order interval. These results are applied to differential operators related to boundary or initial value problems. The goal is to furnish a simple uniform approach, to explain its application, and to provide a kind of survey on what problems have been treated in this way.     

Regularization of Nonlinear Ill-Posed Variational Inequalities and Convergence Rates

Let H be a Hilbert space and K be a nonempty closed convex subset of H. For f H, we consider the (ill-posed) problem of finding u K for which 0 for all v K, where A : H H is a monotone (not necessarily linear) operator. We study the approximation of the solutions of the variational inequality by using the following perturbed variational inequality: for f H, f – f , find u, K for which 0 for all v K, where , , and are positive parameters, and K, a perturbation of the set K, is a nonempty closed convex set in H. We establish convergence and a rate O(1 / 3) of convergence of the solutions of the regularized variational inequalities to a solution of the original variational inequality using the Mosco approximation of closed convex sets, where A is a weakly differentiable inverse-strongly-monotone operator.     

On discrete and continuous norms in Paley-Wiener spaces and consequences for exponential frames

It is well known that for certain sequences {t_n}_n the usual L^p norm ·_p in the Paley-Wiener space PW ^p is equivalent to the discrete norm f_p,{tn}:=( _n=– |f(t_n)|^p)^1/p for 1 p = < and f_,{tn}:=sup _n|f(t_n| for p=). We estimate f_p from above by Cf_p, _n and give an explicit value for C depending only on p, , and characteristic parameters of the sequence {t_n}_n. This includes an explicit lower frame bound in a famous theorem of Duffin and Schaeffer.     

On the almost everywhere convergence of double Fourier series of integrable functions

, . . Q _k [0,2],k=1,2, — . F(x, y)L(T), T=[0, 2]², G(x, y)L(T) , G(x,y)=F(x,y) Q=Q ₁ ×Q ₂ - .     

Über die Häufigkeit großer Differenzen konsekutiver Primzahlen

The following theorem is going to be proved. Letp _m be them-th prime and putd _m :=p _m+1–p _m . LetN(,T), 1/21,T3. denote the number of zeros =+i of the Riemann zeta function which fulfill and ||T. Letc2 andh0 be constants such thatN(,T)T ^c(1–) (logT) ^h holds true uniformly in 1/21. Let >0 be given. Then there is some constantK>0 such that      

On unconditionally convergent basis expansions in the space of continuous functions

[0,1], - H .

---

---

This paper was written during the author's scholarship at the State University of Odessa in the USSR.     

Cones in the space Lp (1 ≤ p ≤ ∞) and minimax problems of mathematical statistics

The structure of cones in the spaces L_p(l p ) and their application to minimax problems of statistical assumptions are considered.Translated from Staticheskie Metody, pp. 28–30, 1978.     

On cubature formulas on the basis of lattices

Q (.. , L). Q . P(S_r(2)) — 2 (S _r(2) (r — ). , M(P(S _r(m=sup{t(·)t(·)₁:t P(S _r(2)),t 0}. , /4+(1)M(P(S _r(2)))/r ²15/17+(1)(r+). (Q), Q L.     

Heegaard spines of 3-manifolds

Summary We describe a procedure to construct a 4-coloured graph representing a closed, connected 3-manifold M starting from a Heegaard diagram of M. As a consequence, we prove that, to each Heegaard diagram of a (closed) 3-manifold M, canonically corresponds a spine (Heegaard spine) of M.     

Spectral synthesis on a system of unbounded domains starlike in a common direction

, . . - ₁, ..., ₄, — ; =(₁,)×...×H(₄), — H(₁, ..., H(₄), r H(₁) — , ₁ ; D: HH- . , D. , ₁..., ₄ , (.. z₁ z+te^ia ₁ t>0), W H .     

Smooth Transformation of the Generalized Minimax Problem

We consider the generalized minimax problem, that is, the problem of minimizing a function (x)=F(g ₁(x),...,g _m(x)), where F is a smooth function and each g _i is the maximum of a finite number of smooth functions. We prove that, under suitable assumptions, it is possible to construct a continuously differentiable exact barrier function, whose minimizers yield the minimizers of the function . In this way, the nonsmooth original problem can be solved by usual minimization techniques for unconstrained differentiable functions.     

Randomly Weighted Sums of Subexponential Random Variables with Application to Ruin Theory

Let {X _k , 1 k n} be n independent and real-valued random variables with common subexponential distribution function, and let {k, 1 k n} be other n random variables independent of {X _k , 1 k n} and satisfying a _k b for some 0 < a b < for all 1 k n. This paper proves that the asymptotic relations P (max_{1 m n k=1} ^m _k X _k > x) P (sum _k=1 ⁿ _k X _k > x) sum _k=1 ⁿ P ( _k X _k > x) hold as x . In doing so, no any assumption is made on the dependence structure of the sequence { _k , 1 k n}. An application to ruin theory is proposed.     

On the Growth of the Maximum of the Modulus of an Entire Function on a Sequence

Let M _f(r) and _f(r) be, respectively, the maximum of the modulus and the maximum term of an entire function f and let be a continuously differentiable function convex on (–, +) and such that x = o((x)) as x +. We establish that, in order that the equality be true for any entire function f, it is necessary and sufficient that ln (x) = o((x)) as x +.     

Weighted Composition Operators on Bergman and Dirichlet Spaces

Let H() denote a functional Hilbert space of analytic functions on a domain . Let w : C and : be such that w f is in H() for every f in H(). The operator wC given by f w f is called a weighted composition operator on H(). In this paper we characterize such operators and those for which (wC )* is a composition operator. Compact weighted composition operators on some functional Hilbert spaces are also characterized. We give sufficient conditions for the compactness of such operators on weighted Dirichlet spaces.     

Thermodynamics,real and complex periods of the Volterra model

The Lotka-Volterra model is converted into a Hamiltonian system. For this system the Gibbs state and the thermodynamic functions as free energy, entropy, expectation and variances of the Hamiltonian and its summands are calculated together with expansions for low and high temperature ^–1.Since the canonical partition functionZ (, , ) is the Laplace transform of the energy-period functionT(E, , ), we obtain expansions ofT (E, , ) for small and large energyE=H (p, q) and arbitrary parameters, by inverse Laplace transformation of the partition functionZ (, , ). Expansions of the partial orbit times T_±±, i.e. the part of the periodT with predator and prey above or below equilibrium values, are available, too. By expressingT(E, , ) as a convolution integral, we derive global inequalities, e. g. the function (log (E/), log (E/)) log (ET) (E, , ) is convex on the whole domainR ² and (E/T) (T/E) (0, 1) globally. Finally the analytic continuation of the functionT=T (E, , ) to the left- as well as right halfplane ReE<0 and ReE>0 can be expressed by Laplace transforms.

---

Zusammenfassung Das Lotka-Volterra Modell wird in ein Hamiltonsches System umgeformt. Für dieses System kann man den Gibbszustand und die thermodynamischen Funktionen wie freie Energie, Entropie sowie Erwartungswerte und Varianzen der Hamiltonfunktion und ihrer Summanden berechnen und Entwicklungen für niedrige als auch hohe Temperatur ^–1 angeben.Da die kanonische ZustandssummeZ (, , ) die Laplacetransformierte der Energie-Perioden FunktionT=T(E, , ) ist, erhält man durch Umkehrung der Laplacetransformation Entwicklungen vonT (E, , ) für kleine sowie große EnergieE=H(p, q). Durch spezielle Manipulationen bekommt man sogar Entwicklungen der PeriodenteileT _±±, das sind die Intervalle während denen Räuber bzw. Beute ober- bzw. unterhalb der Gleichgewichte liegen. Mit Hilfe einer Darstellung vonT(E, , ) als Faltungsintegral beweist man globale Ungleichungen, z. B. ist die Funktion (log (E/), log (E/)) log (ET) (E, , ) auf dem ganzen DefinitionsbereichR ² konvex und (E/T) (T/E) (0,1).Schlußendlich läßt sich die analytische Fortsetzung der FunktionT(E, , ) in die linke sowie rechte Halbebene ReE< 0 bzw. ReE> 0 durch ein Laplaceintegral darstellen.

     

Convergence of random products of compact contractions in Hilbert space

Let {T₁, ..., T_N} be a finite set of linear contraction mappings of a Hilbert space H into itself, and let r be a mapping from the natural numbers N to {1, ..., N}. One can form S_n=T_r(n)...T_r(1) which could be described as a random product of the T_i's. Roughly, the S_n converge strongly in the mean, but additional side conditions are necessary to ensure uniform, strong or weak convergence. We examine contractions with three such conditions. (W): x_n1, Tx_n1 implies (I-T)x_n0 weakly, (S): x_n1, Tx_n1 implies (I-T)x_n0 strongly, and (K): there exists a constant K>0 such that for all x, (I-T)x²K(x²–Tx²).We have three main results in the event that the T_i's are compact contractions. First, if r assumes each value infinitely often, then S_n converges uniformly to the projection Q on the subspace _i= ₁ ^N [x|T_ix=x]. Secondly we prove that for such compact contractions, the three conditions (W), (S), and (K) are equivalent. Finally if S=S(T₁, ..., T_N) denotes the algebraic semigroup generated by the T_i's, then there exists a fixed positive constant K such that each element in S satisfies (K) with that K.     

Algebraic systems of quadratic forms of number fields and function fields

In this paper we examine for which Witt classes ,..., _n over a number field or a function fieldF there exist a finite extensionL/F and ₂,..., _n L^* such thatT _L/F ()=1 andTr _L/F (_i)=_i fori=2,...n.     

Latteninterpolation bei einer Funktion von zwei Veränderlichen

Summary In each lattice point , of a rectangular net a numerical valueu is given. A bicubical and twice continuously differentiable function is constructed interpolating the valuesu . The method is known as «spline interpolation».     

Condition min-∞-N and the representations of solvable groups connected with IT

We study just infinite JG-modules, where J is either the -group algebra or the Ft-group algebra of the infinite cyclic group t over a finite field F and G is a solvable group of finite rank. With the help of the obtained results it is proved that the finitely approximated torsionfree solvable groups with the condition Min-- N are minimax.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 5, pp. 677–681, May, 1990.     

О числе Делителей “Сдвинутых” Простых чисел-Близнецов

.