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On strongly sum-free subsets of abelian groups

Tomasz Łuczak, Tomasz Schoen (1996)

Colloquium Mathematicae

In his book on unsolved problems in number theory [1] R. K. Guy asks whether for every natural l there exists n 0 = n 0 ( l ) with the following property: for every n n 0 and any n elements a 1 , . . . , a n of a group such that the product of any two of them is different from the unit element of the group, there exist l of the a i such that a i j a i k a m for 1 j < k l and 1 m n . In this note we answer this question in the affirmative in the first non-trivial case when l=3 and the group is abelian, proving the following result.

On the Heyde theorem for discrete Abelian groups

G. M. Feldman (2006)

Studia Mathematica

Let X be a countable discrete Abelian group, Aut(X) the set of automorphisms of X, and I(X) the set of idempotent distributions on X. Assume that α₁, α₂, β₁, β₂ ∈ Aut(X) satisfy β α - 1 ± β α - 1 A u t ( X ) . Let ξ₁, ξ₂ be independent random variables with values in X and distributions μ₁, μ₂. We prove that the symmetry of the conditional distribution of L₂ = β₁ξ₁ + β₂ξ₂ given L₁ = α₁ξ₁ + α₂ξ₂ implies that μ₁, μ₂ ∈ I(X) if and only if the group X contains no elements of order two. This theorem can be considered as an analogue...

On the number of abelian groups of a given order (supplement)

Hong-Quan Liu (1993)

Acta Arithmetica

1. Introduction. The aim of this paper is to supply a still better result for the problem considered in [2]. Let A(x) denote the number of distinct abelian groups (up to isomorphism) of orders not exceeding x. We shall prove Theorem 1. For any ε > 0, A ( x ) = C x + C x 1 / 2 + C x 1 / 3 + O ( x 50 / 199 + ε ) , where C₁, C₂ and C₃ are constants given on page 261 of [2]. Note that 50/199=0.25125..., thus improving our previous exponent 40/159=0.25157... obtained in [2]. To prove Theorem 1, we shall proceed along the line of approach presented in [2]....

On the structure of sequences with forbidden zero-sum subsequences

W. D. Gao, R. Thangadurai (2003)

Colloquium Mathematicae

We study the structure of longest sequences in d which have no zero-sum subsequence of length n (or less). We prove, among other results, that for n = 2 a and d arbitrary, or n = 3 a and d = 3, every sequence of c(n,d)(n-1) elements in d which has no zero-sum subsequence of length n consists of c(n,d) distinct elements each appearing n-1 times, where c ( 2 a , d ) = 2 d and c ( 3 a , 3 ) = 9 .

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