Affine invariants, relatively prime sets, and a phi function for subsets of .
Let be a linear form with nonzero integer coefficients Let be an -tuple of finite sets of integers and let be an infinite set of integers. Define the representation function associated to the form and the sets and as follows : If this representation function is constant, then the set is periodic and the period of will be bounded in terms of the diameter of the finite set Other results for complementing sets with respect to linear forms are also proved....
Let be an abelian semigroup, and a finite subset of . The sumset consists of all sums of elements of , with repetitions allowed. Let denote the cardinality of . Elementary lattice point arguments are used to prove that an arbitrary abelian semigroup has polynomial growth, that is, there exists a polynomial such that for all sufficiently large . Lattice point counting is also used to prove that sumsets of the form have multivariate polynomial growth.
A geometric progression of length k and integer ratio is a set of numbers of the form for some positive real number a and integer r ≥ 2. For each integer k ≥ 3, a greedy algorithm is used to construct a strictly decreasing sequence of positive real numbers with a₁ = 1 such that the set contains no geometric progression of length k and integer ratio. Moreover, is a maximal subset of (0,1] that contains no geometric progression of length k and integer ratio. It is also proved that there is...
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