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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Statement

Definitions (printed p. 24): for a sequence S=(s1,s2,…)S=(s_1,s_2,\ldots) of positive integers, P(S)P(S) is the set of all finite sums ∑kεksk\sum_k\varepsilon_ks_k with εk∈{0,1}\varepsilon_k\in\{0,1\}, and SS is complete "if all sufficiently large integers belong to P(S)P(S)". A sequence may repeat a value, and repeated values count separately in P(S)P(S). Square brackets denote the integer part.

Question 12 (printed p. 36, quoted). "Let α\alpha and β\beta be positive reals with α/β\alpha/\beta irrational. Let SS denote the sequence ([α],[β],[2α],[2β],…,[2nα],[2nβ],…)([\alpha],[\beta],[2\alpha],[2\beta],\ldots,[2^n\alpha],[2^n\beta],\ldots). Is SS complete? What if 22 is replaced by some γ\gamma, 1<γ<21<\gamma<2?"

This is the statement of Problem 354 up to notation: the site's multiset {⌊2sα⌋}∪{⌊2tβ⌋}\{\lfloor2^s\alpha\rfloor\}\cup\{\lfloor2^t\beta\rfloor\} is the paper's sequence SS, and the site's second question is the paper's last sentence. The paper offers no result on either question. Its nearest context is Question 2 (printed p. 34): for which (t,α)(t,\alpha) with t>0t>0, 1<α<21<\alpha<2 is the sequence sn=[tαn]s_n=[t\alpha^n] complete, known for 0<t≤10<t\le1 from the author's 1964 Acta Arithmetica paper and, quoted, "Even in the range 1<t<21<t<2, it is not known what happens. Conceivably, SS is complete for all 1<α<1+521<\alpha<\frac{1+\sqrt5}2 and t>0t>0."

Source. R. L. Graham, On sums of integers taken from a fixed sequence, Proceedings of the Washington State University Conference on Number Theory (1971), 22--40; Question 12 on printed p. 36 = PDF p. 15, the definitions on printed p. 24 = PDF p. 3 and Question 2 on printed p. 34 = PDF p. 13 of the author's publication-page scan, read on the page images (the scan has no text layer). The artifact is identified in the source digest.

Read depth. Claims checked: the question, the definitions and Question 2 were read clause by clause on the page images. A question; the paper proves nothing about it. Nothing here is independently reviewed.

Proof pointer

None. The paper asks the question and stops.

Dependencies

None.

Bears on

  • Problem 354: the problem's origin, in the wording the site's statement follows, including the second question with 22 replaced by γ∈(1,2)\gamma\in(1,2).