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Melvyn B. Nathanson

Publications and source records attributed to Melvyn B. Nathanson.

At least 109 records · Page 6Linked to original sources
arXiv2013

Irrational numbers associated to sequences without geometric progressions

Let s and k be integers with s \geq 2 and k \geq 2. Let g_k^{(s)}(n) denote the cardinality of the largest subset of the set {1,2,..., n} that contains no geometric progression of length k whose common ratio is a power of s. Let r_k(\ell) denote the cardinality of the largest subset of the set {0,1,2,\ldots, \ell -1\} that contains no arithmetric progression of length k. The limit \[ \lim_{n\rightarrow \infty} \frac{g_k^{(s)}(n)}{n} = (s-1) \sum_{m=1}^{\infty} \left(\frac{1}{s} \right)^{\min \left(r_k^{-1}(m)\right)} \] exists and converges to an irrational number.

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arXiv2013

Cantor polynomials for semigroup sectors

A packing function on a set Omega in R^n is a one-to-one correspondence between the set of lattice points in Omega and the set N_0 of nonnegative integers. It is proved that if r and s are relatively prime positive integers such that r divides s-1, then there exist two distinct quadratic packing polynomials on the sector {(x,y) \in \R^2 : 0 \leq y \leq rx/s}. For the rational numbers 1/s, these are the unique quadratic packing polynomials. Moreover, quadratic quasi-polynomial packing functions are constructed for all rational sectors.

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arXiv2013

On the fractional parts of roots of positive real numbers

Let [θ] denote the integer part and θ the fractional part of the real number θ. For θ> 1 and {θ^{1/n}} \neq 0, define M_θ(n) = [1/{θ^{1/n}}]. The arithmetic function M_θ(n) is eventually increasing, and \lim_{n\rightarrow \infty} M_θ(n)/n = 1/\log θ. Moreover, M_θ(n) is "linearly periodic" if and only if \log θis rational. Other results and problems concerning the function M_θ(n) are discussed.

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arXiv2013

Additive systems and a theorem of de Bruijn

This paper gives a complete proof of a theorem of de Bruijn that classifies additive systems for the nonnegative integers, that is, families $\mca = (A_i)_{i\in I}$ of sets of nonnegative integers, each set containing 0, such that every nonnegative integer can be written uniquely in the form $\sum_{i\in I} a_i$ with $a_i \in A_i$ for all $i$ and $a_i \neq 0$ for only finitely many $i$. All indecomposable additive systems are determined.

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arXiv2011

Geometric group theory and arithmetic diameter

Let X be a group with identity e, let A be an infinite set of generators for X, and let (X,d_A) be the metric space with the word metric d_A induced by A. If the diameter of the space is infinite, then for every positive integer h there are infinitely many elements x in X with d_A(e,x)=h. It is proved that if P is a nonempty finite set of prime numbers and A is the set of positive integers whose prime factors all belong to P, then the diameter of the metric space (\Z,d_A) is infinite. Let λ_A(h) denote the smallest positive integer x with d_A(e,x)=h. It is an open problem to compute λ_A(h) and estimate its growth rate.

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arXiv2011

On a partition problem of Canfield and Wilf

Let A and M be nonempty sets of positive integers. A partition of the positive integer n with parts in A and multiplicities in M is a representation of n in the form n = \sum_{a\in A} m_a a, where m_a is in M U {0} for all a in A, and m_a is in M for only finitely many a. Denote by p_{A,M}(n) the number of partitions of n with parts in A and multiplicities in M. It is proved that there exist infinite sets A and M of positive integers whose partition function p_{A,M} has weakly superpolynomial but not superpolynomial growth. The counting function of the set A is A(x) = \sum_{a \in A, a\leq x} 1. It is also proved that p_{A,M} must have at least weakly superpolynomial growth if M is infinite and A(x) >> log x.

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arXiv2009

Shatrovskii's construction of thin bases

The set A of nonnegative integers is called a basis of order h if every nonnegative integer can be represented as the sum of exactly h not necessarily distinct elements of A. An additive basis A of order h is called thin if there exists c > 0 such that the number of elements of A not exceeding x is less than cx^{1/h} for all x > 0. This paper describes a construction of Shatrovskii of thin bases of order h.

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arXiv2009

An inverse problem in number theory and geometric group theory

This paper describes a new link between combinatorial number theory and geometry. The main result states that A is a finite set of relatively prime positive integers if and only if A = (K-K) \cap N, where K is a compact set of real numbers such that for every real number x there exists y in K with x \equiv y mod 1. In one direction, given a finite set A of relatively prime positive integers, the proof constructs an appropriate compact set K such that A = (K-K) \cap N. In the other direction, a strong form of a fundamental theorem in geometric group theory is applied to prove that (K-K)\cap N is a finite set of relatively prime positive integers if K satisfies the appropriate geometrical conditions. Some related results and open problems are also discussed.

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arXiv2009

Cassels bases

This paper describes several classical constructions of thin bases of finite order in additive number theory, and, in particular, gives a complete presentation of a beautiful construction of J. W. S. Cassels of a class of polynomially asymptotic bases. Some open problems are also discussed.

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arXiv2009

Bi-Lipschitz equivalent metrics on groups, and a problem in additive number theory

There is a standard "word length" metric canonically associated to any set of generators for a group. In particular, for any integers a and b greater than 1, the additive group of integers has generating sets {a^i}_{i=0}^{\infty} and {b^j}_{j=0}^{\infty} with associated metrics d_A and d_B, respectively. It is proved that these metrics are bi-Lipschitz equivalent if and only if there exist positive integers m and n such that a^m = b^n.

math.MG↗
arXiv2008

Nets in groups, minimum length $g$-adic representations, and minimal additive complements

The number theoretic analogue of a net in metric geometry suggests new problems and results in combinatorial and additive number theory. For example, for a fixed integer g > 1, the study of h-nets in the additive group of integers with respect to the generating set A_g = {g^i:i=0,1,2,...} requires a knowledge of the word lengths of integers with respect to A_g. A g-adic representation of an integer is described that algorithmically produces a representation of shortest length. Additive complements and additive asymptotic complements are also discussed, together with their associated minimality problems.

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arXiv2008

Phase transitions in infinitely generated groups, and related problems in additive number theory

Let A be an infinite set of generators for a group G, and let L_A(r) denote the number of elements of G whose word length with respect to A is exactly r. The purpose of this note is to determine all growth functions L_A(r) associated to infinite generating sets for groups, and to describe a phase transition phenomenon associated with infinite generating sets. A list of open problems is also.included.

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arXiv2008

Desperately seeking mathematical truth

This article discusses epistemological problems in the philosophy of mathematics and issues concerning the reliability of the mathematical literature.

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arXiv2008

Supersequences, rearrangements of sequences, and the spectrum of bases in additive number theory

The set A = {a_n} of nonnegative integers is an asymptotic basis of order h if every sufficiently large integer can be represented as the sum of h elements of A. If a_n ~ alpha n^h for some real number alpha > 0, then alpha is called an additive eigenvalue of order h. The additive spectrum of order h is the set N(h) consisting of all additive eigenvalues of order h. It is proved that there is a positive number eta_h <= 1/h! such that N(h) = (0, eta_h) or N(h) = (0, eta_h]. The proof uses results about the construction of supersequences of sequences with prescribed asymptotic growth, and also about the asymptotics of rearrangements of infinite sequences. For example, it is proved that there does not exist a strictly increasing sequence of integers B = {b_n} such that b_n ~ 2^n and B contains a subsequence {b_{n_k}} such that b_{n_k} ~ 3^k.

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arXiv2008

Linear forms and complementing sets of integers

Let $φ(x_1,\ldots,x_h,y) = u_1x_1 + \cdots + u_hx_h+vy$ be a linear form with nonzero integer coefficients $u_1,\ldots, u_h, v.$ Let $\mathcal{A} = (A_1,\ldots, A_h)$ be an $h$-tuple of finite sets of integers and let $B$ be an infinite set of integers. Define the representation function associated to the form $φ$ and the sets \mca\ and $B$ as follows: $$ R^{(φ)}_{\mathcal{A},B}(n) = \text{card}\left( \left\{ (a_1,\ldots, a_h,b) \in A_1 \times \cdots \times A_h \times B: φ(a_1, \ldots , a_h,b ) = n \right\} \right).$$ If this representation function is constant, then the set $B$ is periodic and the period of $B$ will be bounded in terms of the diameter of the finite set $\{ φ(a_1,\ldots,a_h,0): (a_1,\ldots, a_h) \in A_1 \times \cdots \times A_h\}.$

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