A Generalization of the Gallai–Roy Theorem

 A well-known and essential result due to Roy ([4], 1967) and independently to Gallai ([3], 1968) is that if D is a digraph with chromatic number χ(D), then D contains a directed path of at least χ(D) vertices. We generalize this result by showing that if ψ(D) is the minimum value of the number of the vertices in a longest directed path starting from a vertex that is connected to every vertex of D, then χ(D) ≤ψ(D). For graphs, we give a positive answer to the following question of Fajtlowicz: if G is a graph with chromatic number χ(G), then for any proper coloring of G of χ(G) colors and for any vertex v∈V(G), there is a path P starting at v which represents all χ(G) colors. Received: May 20, 1999 Final version received: December 24, 1999     

A Generalization of a Theorem of Liao

Let X be a metrizable space and let φ：R× X → X be a continuous flow on X. For any given {φt}-invariant Borel probability measure, this paper presents a {φt}-invariant Borel subset of X satisfying the requirements of the classical ergodic theorem for the contiImous flow （X, {φt}）. The set is more restrictive than the ones in the literature, but it might be more useful and convenient, particularly for non-uniformly hyperbolic systems and skew-product flows.     

A Generalization of the Siegel–Walfisz Theorem and its Application

We investigate the distribution of integers with a fixed number of prime factors in arithmetic progressions, and obtain a generalization of the Siegel–Walfisz theorem under the extended Riemann hypothesis. As an application, we consider a problem of P. Erd?s, A. M. Odlyzko and A. Sárközy about the representation of residue classes modulo q by products of two integers with a fixed number of prime factors. We show some conditional results.     

A Generalization of the Poincaré--Bendixson Theorem for Compact 3-manifolds

It is shown that compressible cylindrical ends in compact foliated 3-manifolds spiral onto toral leaves.Mathematics Subject Classification (2000).57R30, 57M99.     

A Generalization of Takegoshi’s Relative Vanishing Theorem

We present a generalization of Takegoshi’s relative version of the Grauert–Riemenschneider vanishing theorem. Under some natural assumptions, we extend Takegoshi’s vanishing theorem to the case of Nakano semi-positive coherent analytic sheaves on singular complex spaces. We also obtain some new results about proper modifications of torsion-free coherent analytic sheaves.     

A Generalization of Strassen’s Theorem on Preordered Semirings

Order - Given a commutative semiring with a compatible preorder satisfying a version of the Archimedean property, the asymptotic spectrum, as introduced by Strassen (J. reine angew. Math. 1988), is...     

A Uniqueness Theorem of Meromorphic Maps and a Generalization of the Borel’s Lemma

This paper gives a generalization of the classical Borel's Lemma. Then as an application of this generalized Borel's Lemma, a uniqueness theorem for two linearly non-degenerate meromorphic maps of C^m into Pⁿ(C) (n ≥ 2) sharing 2n + 2 hyperplanes in general position is proved.     

RESEARCH ANNOUNCEMENTS A Generalization if Goldie's Theorem

In this paper we proved two theorems which are generalizations of Goldie’sTheorem, Definition 1.A ring R is said to be a right G-ring,if R satisfies (i)For any nonezero left ideal L of R,there exists 0≠x∈L,for any S,t∈R, st≠0,xt≠0 imply sxt≠0. (ii)For any x∈R,the right Goldie’s dimension of xR is finite. Definition 2.Let Δ be a division ring and N be a veetor space over Δ,a     

A Generalization of Schep’s Theorem on the Positive Definiteness of a Piecewise Linear Function

Mathematical Notes - Schep proved that, for a piecewise linear function with nodes at integer points, positive definiteness on ? is equivalent to positive definiteness on ?. In this...     

Zero Duality Gap for Convex Programs: A Generalization of the Clark–Duffin Theorem

This article uses classical notions of convex analysis over Euclidean spaces, like Gale & Klee’s boundary rays and asymptotes of a convex set, or the inner aperture directions defined by Larman and Brøndsted for the same class of sets, to provide a generalization of the Clark–Duffin Theorem. On this ground, we are able to characterize objective functions and, respectively, feasible sets for which the duality gap is always zero, regardless of the value of the constraints and, respectively, of the objective function.     

Dually Degenerate Varieties and the Generalization of a Theorem of Griffiths–Harris

The dual variety X^* for a smooth n-dimensional variety X of the projective space P^N is the set of tangent hyperplanes to X. In the general case, the variety X^* is a hypersurface in the dual space (P^N)^*. If dimX^*<N–1, then the variety X is called dually degenerate. The authors refine these definitions for a variety XP^N with a degenerate Gauss map of rankr. For such a variety, in the general case, the dimension of its dual variety X^* is N–l–1, where l=n–r, and X is dually degenerate if dimX^*<N–l–1. In 1979 Griffiths and Harris proved that a smooth variety XP^N is dually degenerate if and only if all its second fundamental forms are singular. The authors generalize this theorem for a variety XP^N with a degenerate Gauss map of rankr. Mathematics Subject Classification (2000) 53A20.     

On a Generalization of Voronin’s Theorem

Mathematical Notes - Voronin’s theorem states that the Riemann zeta-function ζ(s) is universal in the sense that all analytic functions that are defined and have no zeros on the right...     

A Generalization of Bochner’s Extension Theorem to Rough Tubes

This paper generalizes Bochner’s extension theorem to tubes X+iℝ ^m where the set X⊂ℝ ^m is not necessarily a manifold.     

A Generalization of Algebraic Lattices

In this paper,we prove two theorems on lattices and operators.Definition Let L be a complete lattice.An element a in L is(＊)-compact if and only 1if whenever a≤VA for A(?)L then a≤VB for some B(?)Awith B is at most countable.L is called(＊)—algebraic lattice if every element in L is a supremum of(＊)—compactelements.(＊)—algebraic lattice is a generalization of algebraic lattice.     

A Generalization of the Logarithmic Gross–Sobolev Inequality

Doklady Mathematics - A sharp integral inequality is proved that is used to derive a Sobolev interpolation inequality. A generalization of the logarithmic Sobolev inequality is proposed based on...     

On a Generalization of Rédei’s Theorem

In 1970 Rédei and Megyesi proved that a set of p points in AG(2,p), p prime, is a line, or it determines at least directions. In 81 Lovász and Schrijver characterized the case of equality. Here we prove that the number of determined directions cannot be between and . The upper bound obtained is one less than the smallest known example.     

A Generalization of the Karush–Kuhn–Tucker Theorem for Approximate Solutions of Mathematical Programming Problems Based on Quadratic Approximation

In computations related to mathematical programming problems, one often has to consider approximate, rather than exact, solutions satisfying the constraints of the problem and the optimality criterion with a certain error. For determining stopping rules for iterative procedures, in the stability analysis of solutions with respect to errors in the initial data, etc., a justified characteristic of such solutions that is independent of the numerical method used to obtain them is needed. A necessary δ-optimality condition in the smooth mathematical programming problem that generalizes the Karush–Kuhn–Tucker theorem for the case of approximate solutions is obtained. The Lagrange multipliers corresponding to the approximate solution are determined by solving an approximating quadratic programming problem.