Remarks on some zero-sum problems

Let Z denote the ring of integers and for a prime p and positive integers r and d, let f_r(P, d) denote the smallest positive integer such that given any sequence of f_r(p, d) elements in (Z/pZ(^d, there exists a subsequence of (rp) elements whose sum is zero in (Z/pZ(^d. That f₁(p, 1) = 2p − 1, is a classical result due to Erdős, Ginzburg and Ziv. Whereas the determination of the exact value of f₁(p, 2) has resisted the attacks of many well known mathematicians, we shall see that exact values of f_r(p, 1) for r ≥ 1 can be easily obtained from the above mentioned theorem of Erdős, Ginzburg and Ziv and those of f_r(p, 2) for r ≥ 2 can be established by the existing techniques developed by Alon, Dubiner and Rónyai in connection with obtaining good upper bounds for f₁(p, 2). We shall also take this opportunity to describe some of the early results in the introduction.     

Contributions to zero-sum problems

A prototype of zero-sum theorems, the well-known theorem of Erd?s, Ginzburg and Ziv says that for any positive integer n, any sequence a₁,a₂,…,a_2n-1 of 2n-1 integers has a subsequence of n elements whose sum is 0 modulo n. Appropriate generalizations of the question, especially that for (Z/pZ)^d, generated a lot of research and still have challenging open questions. Here we propose a new generalization of the Erd?s-Ginzburg-Ziv theorem and prove it in some basic cases.     

On certain conjectures on invariant measures on semigroups

A conjecture stating that a locally compact semigroup admits a twosided semi-invariant measure iff it contains a kernel which is a unimodular group, is proven. Also a conjecture stating that the support of an r^*-invariant measure is a left group, is proven under the condition that for some a ε F (=support of the measure), aF is right cancellative. Moreover four types of invariance for regular probability measures are shown to be equivalent. Also a new proof of the equivalence of a two-sided semi-invariant probability measure and the existence of a kernel which is a compact group, is given.     

Open problems and conjectures

In this section we present some pen problems and conjectures about some interesting types of difference equations. Please submit your problems and conjectures with all relevant information to G. Ladas.     

Open problems and conjectures

In this section we present some open problems and conjectures about some interesting types of difference equations, Please submit your problems and conjectures with all relevant information to G. Ladas.     

Open problems and conjectures

In this section we present some open problems and conjectures about some interesting types of difference equations. Please submit your problems and conjecutures with all relevant informations to G. Ladas     

On three zero-sum Ramsey-type problems

For a graph G whose number of edges is divisible by k, let R(G,Z_k) denote the minimum integer r such that for every function f: E(K_r) ? Z_k there is a copy G¹ of G in K_r so that Σe∈E(G¹) f(e) = 0 (in Z_k). We prove that for every integer k₁ R(K_n, Z_k) ≤ n + O(k³ log k) provided n is sufficiently large as a function of k and k divides (). If, in addition, k is an odd prime-power then R(K_n, Z_k) ≤ n + 2k - 2 and this is tight if k is a prime that divides n. A related result is obtained for hypergraphs. It is further shown that for every graph G on n vertices with an even number of edges R(G,Z₂) ≤ n + 2. This estimate is sharp. © 1993 John Wiley & Sons, Inc.     

Open problems and conjectures

In this section we present some open problems and conjectures about some interesting types of difference equations. Please submit your problems and conjectures with all relevant information to G. Ladas.     

Open problems and conjectures

In this section we present some open problems and conjectures about some interesting types of difference equations. Please submit your problems and conjectures with all relavant information to G.Ladas     

Open problems and conjectures

Two conjectures are made about the dynamics of SI and SIR epidemic models     

Value of information in two-team zero-sum problems

The situation in which two groups of people have conflicts of interest is considered as a two-team zero-sum game problem. Two special cases of this problem are solved to illustrate that communication among members of a team may not be worth-while and extra information need not always be desired by decision makers. In the appendix, it is shown that the optimal saddle-point solution exists and is still affine for the general problem with quadratic Gaussian performance index.Dedicated to Professor M. R. HestenesThe research reported in this paper was made possible through support extended to the Division of Engineering and Applied Physics, Harvard University, by the U.S. Office of Naval Research under the Joint Services Electronics Program, Contract No. N00014-67-A-0298-0006, and by the National Science Foundation, Grant No. GK-31511.     

Some problems and conjectures in number theory

In this article, we shall discuss some interesting, viable, meaningful, applicable and productive conjectures and methods to deal with some fundamental results in the theory of numbers.     

On some conjectures on generalized quadratic Gauss sums and related problems

The main purpose of this article is to study higher power mean values of generalized quadratic Gauss sums using estimates for character sums, analytic methods and algebraic geometric methods. We prove two conjectures which were proposed recently by the above authors in a previous article (2022). Here we obtain an asymptotic formula for arbitrary power means of generalized quadratic Gauss sums and one corresponding power moment of a character sum.     

A Diophantine approach to the three and four exponentials conjectures

Some special cases of Wilkie’s conjecture are shown to be equivalent to real versions of the three and four exponentials conjectures. Wilkie’s conjecture is an open problem originating in model theory that concerns the density of algebraic points in sets defined using the exponential function; the latter conjectures concern the algebraic nature of values of the exponential function.     

Open problems and conjectures,optimal rearrangement problems related to discrete loaded strings

In this section we present some open problems and conjectures about some interesting types of difference equations. Please submit your problems and conjectures with all relevant information to G. Ladas.     

Formulation and analysis of combat problems as zero-sum bicriterion differential games

In this paper, we present a formulation and analysis of a combat game between two players as a zero-sum bicriterion differential game. Each player's twin objectives of terminating the game on his own target set, while simultaneously avoiding his opponent's target set, are quantified in this approach. The solution in open-loop pure strategies is sought from among the Pareto-optimal security strategies of the players. A specific preference ordering on the outcomes is used to classify initial events in the assured win, draw, and mutual kill regions for the players. The method is compared with the event-constrained differential game approach, recently proposed by others. Finally, a simple example of the turret game is solved to illustrate the use of this method.