Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.
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Claim. Theorem 1.4 of Feng (p. 3 of arXiv v3; the journal's Theorem 1.4) is printed as "If and is not a Pisot number, then . In particular, if and is not a Pisot number, then ", where is the upper limit of the consecutive gaps of the ordered sums of powers of with digits ; for the sequence is the of Problem 1096 and says . The paper derives the theorem in one line from its Corollary 1.3 (, the lower limit of the gaps, exactly when and is not Pisot, a corollary of the main density theorem) and the implication , Lemma 2.5 of Akiyama and Komornik, first proved for as Theorem 5 of the 1998 Acta Arithmetica paper of Erdős, Joó and Komornik. The result first appears in arXiv v2 as Proposition 3.1 of Section 3.2, for general , with the case stated there for and the range credited to Akiyama and Komornik; v3 and the journal print it as Theorem 1.4 in the form quoted above. arXiv v1 states neither: its Theorem 1.4 concerns finite accumulation points of and it does not define . The deduction to the problem: the smallest Pisot number is , the real root of (Siegel's theorem of 1944, which the site's commentary also states), so no Pisot number lies in ; for one has , hence is not Pisot, and , so Theorem 1.4 with gives . Since , every answers the question: yes. Feng's paper does not state this consequence, as the site's curator observes in the thread; the deduction is the one paragraph above, made on the problem page and in the curator's thread post. The theorem is compiled on the result page theorem_1_4; the digest is on the card feng_2016_topology_polynomials_bounded_integer_coefficients.
Scope of the theorem. Theorem 1.4 decides every except the square roots of Pisot numbers (, , and so on), where it is silent; the earlier Theorem IV on [[problems/number_theory/E1096/claims/1998_04_01_erdos_komornik|Erdős and Komornik's page]] covers by a separate case and leaves out below , a point closed by Theorem 1.4 (i) on Akiyama and Komornik's page, which gives for every . The three pages give the same answer by routes through or , and none rests on another.
Acceptance. Refereed: De-Jun Feng, On the topology of polynomials with bounded integer coefficients, J. Eur. Math. Soc. (JEMS) 18 (2016), no. 1, 181--193, whose Crossref record dates the article 16 December 2015; the page is named by the first arXiv posting that carries the claim, 1109.1407v2 of 10 November 2011 (as Proposition 3.1; v1 of 7 September 2011 does not contain it), and the text cited is v3 of 1 February 2015, not compared with the journal text. Reviewed: the site's curator, Thomas F. Bloom, wrote in the problem's thread on 16 April 2026 that the problem was solved by Feng, through Theorem 1.4 and the gap between and the smallest Pisot number, before finding the earlier resolution of Erdős and Komornik, and the problem's commentary states both of Feng's results; the curator neither wrote nor submitted the result. Read depth: claims checked for Theorem 1.4, Corollary 1.3, Theorem 1.2 and the derivation sentence; Feng's proof (Theorem 1.6 by way of Theorem 1.11, pp. 5--6, and Section 2, pp. 6--11) and the cited implication are not checked, and nothing here is independently reviewed by this project.
Depends on. Nothing on the wiki; the deduction uses Siegel's theorem on the smallest Pisot number, cited on the problem page as [Si44], a classical fact that is not compiled here.