Large transversals to small families of unit disks

Summary It is proved that if the nonempty intersection of bounded closed convex sets AnB is contained in (A + F)U(B+F) and one of the following holds true: (i) the space X is less-than-three dimensional, (ii) AUB is convex, (iii) F is a one-point set, then AnBCA+F or AnBCB+F (Theorems 2 and 3). Moreover, under some hypotheses the characterization of A and B such that AnB is a summand of AUB is given (Theorem 3).     

Role of information in the stochastic zero-sum differential game

In this paper, a linear-quadratic Gaussian zero-sum differential game is studied. Maneuverability is defined to measure players' strength. It is shown that a more maneuverable player would prefer a more observable information system. An example is given to show that a more controllable player might not prefer more observable measurements in the stochastic environment.The research reported in this paper was made possible through support extended to the Division of Engineering and Applied Physics, Harvard University, by the US Office of Naval Research under the Joint Services Electronics Program by Contract No. N00014-75-c-0648 and by the National Science Foundation under Grant No. GK31511.     

A new class of cutting planes for the symmetric travelling salesman problem

A comprehensive class of cutting planes for the symmetric travelling salesman problem (TSP) is proposed which contains the known comb inequalities, the path inequalities and the 3-star constraints as special cases. Its relation to the clique tree inequalities is discussed. The cutting planes are shown to be valid for a relaxed version of the TSP, the travelling salesman problem on a road network, and—under certain conditions—to define facets of the polyhedron associated with this problem.     

Stellare Abänderungen und Schälbarkeit von Komplexen und Polytopen

Brugesser and Mani proved that the boundary-complex of a convex polytope can be shelled. This result lead to McMullen's proof of the Upper-bound-conjecture. We show that the shellability of complexes has a close connection to the theory of stellar operations. Several results on special shelling procedures and on non-shellable complexes are obtained.     

Weyl's theorem for operator matrices

Weyl's theorem holds for an operator when the complement in the spectrum of the Weyl spectrum coincides with the isolated points of the spectrum which are eigenvalues of finite multiplicity. By comparison Browder's theorem holds for an operator when the complement in the spectrum of the Weyl spectrum coincides with Riesz points. Weyl's theorem and Browder's theorem are liable to fail for 2×2 operator matrices. In this paper we explore how Weyl's theorem and Browder's theorem survive for 2×2 operator matrices on the Hilbert space.Supported in part by BSRI-97-1420 and KOSEF 94-0701-02-01-3.     

On term by term dyadic differentiability of Walsh series

. . . . : {ja _j },j=1,2,... — , f(x) , , f ^[1](x) — f .     

The Cesàro-Denjoy-Bochner scale of almost periodicity

, —— , . , f, ——, —. .     

Previsible sets for hyperfinite filtrations

Summary Previsible (or predictable) stochastic processes are defined for any filtration over a probability space (Dellacherie and Meyer (1978), IV. 61). This technical definition gives previsible processes certain predictability properties such as not being able to oscillate in unison with martingale differentials. Thus previsibility has become one essential ingredient in The General Theory of Stochastic Processes.We show that previsible sets for Keisler's (1984) special hyperfinite filtration are given both combinatorially and by a left filtration. Keisler's scheme has many other interesting features.Our main technical tool is an extension of Henson's (1979) analysis of analytic sets and the standard part map.     

A Kantorovich-type convergence analysis for the Gauss-Newton-Method

Summary We present a (semilocal) Kantorovich-type convergence analysis for the Gauss-Newton-Method which reduces to the wellknown Newton-Kantorovich-Theorem for the Newton-Method in a natural way. Additionnally a classification of the nonlinear regression problem into adequate and not-adequate models is obtained.     

A generalized Laplace transform of generalized functions

- . . . , .     

Some inequalities of Hardy-Littlewood type

[3] , >0 n ^– a _n , . , . . , .

---

---

This research was partially supported by the Hungarian National Foundation for Scientific Research under Grant #234.     

Asymptotics at t→∞ of the solution of the Cauchy problem for the Landau-Lifshitz equation

Conclusions The formulas obtained in the present paper for the leading term in the asymptotic behavior of the solution of the Cauchy problem for the LL equation subject to the boundary conditions L₃1, x± describe the solitonless sector. The transition to the general case, which takes into account the presence in the solution of soliton formations, can be made on the basis solely of algebraic considerations that use the procedure of soliton dressing developed in [17, 18] for the LL equation. In particular, applying to the obtained asymptotic formulas the procedure for a dressing of domain wall type (see [17]), we arrive at formulas that describe the asymptotic solution of the Cauchy problem for the LL equation with boundary conditions of the form L₃±1, x±.Leningrad State University. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 76, No. 1, pp. 3–17, July, 1988.     

Remark on the Helly number for strongly convex sets on Riemannian manifolds

Replacing convex by strongly convex we show that Helly's famous intersection theorem holds on every Riemannian n-manifold in the following form: The intersection of k relatively compact, strongly convex subsets of M (kn+i2) is nonvoid as soon as any n+i of these sets have a nonvoid intersection, where i=2 if M is homeomorphic to the standard n-sphere and i=1 otherwise.     

The rank of a commutative cancellative semigroup

Summary For a commutative cancellative semigroup S, we define the rank of S intrinsically. This definition implies that the rank of S equals the usual rank of its group of quotients. We also characterize the rank in terms of embeddability into a rational vector space of the greatest power cancellative image of S.     

О несколвких принципиальных вопросах задач о цоБственных значениях отосительно систем Дифференциальных уравнений. I

Summary In the course of the numerical solution of Eigenvalue-problems connected with linear differential equations, the so-called encompassing theorems are of great importantce. We generalize in this paper the most important results of the theory, especially the encompassing-theorems, to the case of systems of differential equations. We expound further a method of perturbation which can be well applied also in the practice for the solution of Eigenvalue-problems connected with the systems. The problem acrose in connection with the fixation of the number of critical self-oscillation of turbine shovels.

---

---

.      

On a retract of an integral domain

Let A R be commutative integral domains with identity. We say A is a retract of R when there exists a ring homomorphism : RA such that |_A=id_A. We Prove two theorems: Theorem 3.1 says when A is a retract of R via , with Kernel ()= =t·R (O), then t is transcendental over A and if A is sub-inert in R, then RK(t)=A[t], where K is the quotient field of A. This theorem with the hypotheses strengthened to A being a 2-valuation algebra of R and the transcendence degree of R over A equal to one, gives Theorem 4.1, which now says R=A[t]. Given the other hypotheses of Theorem 4.1, A being a 2-valuation algebra of R is equivalent to the existence of a valuation ring V of L, the quotient field of R, such that VR=A. Some counterexamples are given and some variations on the hypotheses of Theorem 4.1 are discussed.     

Chapter 1 Introduction: Extensions and new developments in DEA

The extensions, new developments and new interpretations for DEA covered in this paper include: (1) new measures of efficiency, (2) new models and (3) new ways of implementing established models with new results and interpretations presented that include treatments of congestion, returns-to-scale and mix and technical inefficiencies and measures of efficiency that can be used to reflect all pertinent properties. Previously used models, such as those used to identify allocative inefficiencies, are extended by means of assurance region approaches which are less demanding in their information requirements and underlying assumptions. New opportunities for research are identified in each section of this chapter. Sources of further developments and possible sources for further help are also suggested with references supplied to other papers that appear in this volume and which are summarily described in this introductory chapter.     

Extension of functions,which are traces of functions belonging to 249-01249-01249-01on an arbitrary subset of the line

( , k) , ER f(x) f(x)H _k (R) (k2— ,=(t) — k- ). f(x) E (t).     

On the distribution of points of maximal deviation in complex Čebyšev approximation

f — , . p _n (f) f . , n+2 , f–p _n (f) . , n . , .

---

On the distribution of points of maximal deviation in complex ebyev approximation

     

Spectral orders and convolution

. (R) _{– –} fg(y)h(x–y) dx dy _{– –} f ^{^} (x)g ^{^} (y)h ^{^} (x–y)dx dy (f,g0) —:f×gf ^{^} ×g ^{^}(f,g 0) f^{^} g^{^} f g -, X — . , - f ₁f ₂ , f ₁ ^{^} ×gf ₂×g 0g. .