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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

Setting (p. 11). Fix an integer p≥2p\ge2. For an integer N≥1N\ge1, a minimal additive complement of the pp-th powers up to NN is a subset BB of {0,1,…,N}\{0,1,\ldots,N\} of smallest cardinality such that every integer nn with 1≤n≤N1\le n\le N is b+kpb+k^p for some b∈Bb\in B and some integer kk. Its cardinality is bp(N)b_p(N), and α(p)\alpha(p) is the liminf, as N→∞N\to\infty, of bp(N)/N1−1/pb_p(N)/N^{1-1/p}; the print writes b(N)b(N) in this definition where the context calls for bp(N)b_p(N).

Theorem (p. 11, unnumbered, quoted). "If, for a δ\delta in the interval (0,1)(0,1) and all large integers NN, there is a minimal additive complement of the pp-th powers up to NN contained in the interval [0,δN][0,\delta N], then one has the following inequality." The inequality, displayed as (20):

α(p)≥p1−δ1−1p(1−δ)1−1p+(1−1p)∫0δdtt1−1p(1−t)1p.(20)\alpha(p)\ge\frac{p}{\dfrac{1-\delta^{1-\frac1p}}{(1-\delta)^{1-\frac1p}} +\Bigl(1-\dfrac1p\Bigr)\displaystyle\int_0^\delta \frac{dt}{t^{1-\frac1p}(1-t)^{\frac1p}}}. \qquad(20)

The paper calls this the generalization of Theorem 1 to higher powers, says the method of the note adapts easily, and records the statement for completeness; it gives no proof.

Consistency checks (observations of this page, not of the paper). For p=2p=2 the right side of (20) is the right side of Theorem 1's inequality (1), since (1−δ)/1−δ=1−δ/(1+δ)(1-\sqrt\delta)/\sqrt{1-\delta}=\sqrt{1-\delta}/(1+\sqrt\delta) and 12∫0δdt/t(1−t)=sin⁡−1δ\tfrac12\int_0^\delta dt/\sqrt{t(1-t)}=\sin^{-1}\sqrt\delta, the two identities the paper uses on p. 10. As δ→0\delta\to0 the right side tends to pp; as δ→1\delta\to1 the first term of the denominator tends to 00 and the integral to π/sin⁡(π/p)\pi/\sin(\pi/p), so the right side tends to p2sin⁡(π/p)/((p−1)π)p^2\sin(\pi/p)/((p-1)\pi), which is 4/π4/\pi at p=2p=2.

Source. R. Balasubramanian and D. S. Ramana, Additive complements of the squares, C. R. Math. Rep. Acad. Sci. Canada 23 (2001), no. 1, 6-11: Section 5 (Concluding Remarks), p. 11. The edition read is identified on the source card.

Read depth. Claims checked: the setting and the statement were read clause by clause on the printed page. The paper prints no proof, so none was checked. Nothing here is independently reviewed.

Proof pointer

None in the paper. It states (p. 11) that the method used for Theorem 1 adapts easily to pp-th powers.

Dependencies

The method of Theorem 1 of the same paper.

Bears on

  • Problem 33: only through the case p=2p=2, where the statement coincides with Theorem 1, whose page states the relation. The cases p≥3p\ge3 concern complements of higher powers, which Problem 33 does not ask about.