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Representation of finite abelian group elements by subsequence sums

David J. Grynkiewicz, Luz E. Marchan, Oscar Ordaz (2009)

Journal de Théorie des Nombres de Bordeaux

Let G C n 1 ... C n r be a finite and nontrivial abelian group with n 1 | n 2 | ... | n r . A conjecture of Hamidoune says that if W = w 1 · ... · w n is a sequence of integers, all but at most one relatively prime to | G | , and S is a sequence over G with | S | | W | + | G | - 1 | G | + 1 , the maximum multiplicity of S at most | W | , and σ ( W ) 0 mod | G | , then there exists a nontrivial subgroup H such that every element g H can be represented as a weighted subsequence sum of the form g = n i = 1 w i s i , with s 1 · ... · s n a subsequence of S . We give two examples showing this does not hold in general, and characterize the counterexamples...

Restricted set addition in Abelian groups: results and conjectures

Vsevolod F. Lev (2005)

Journal de Théorie des Nombres de Bordeaux

We present a system of interrelated conjectures which can be considered as restricted addition counterparts of classical theorems due to Kneser, Kemperman, and Scherk. Connections with the theorem of Cauchy-Davenport, conjecture of Erdős-Heilbronn, and polynomial method of Alon-Nathanson-Ruzsa are discussed.The paper assumes no expertise from the reader and can serve as an introduction to the subject.

Small-sum pairs in abelian groups

Reza Akhtar, Paul Larson (2010)

Journal de Théorie des Nombres de Bordeaux

Let G be an abelian group and A , B two subsets of equal size k such that A + B and A + A both have size 2 k - 1 . Answering a question of Bihani and Jin, we prove that if A + B is aperiodic or if there exist elements a A and b B such that a + b has a unique expression as an element of A + B and a + a has a unique expression as an element of A + A , then A is a translate of B . We also give an explicit description of the various counterexamples which arise when neither condition holds.

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