Pub Date : 2025-12-29DOI: 10.1016/j.jnt.2025.11.014
Bikram Misra , M. Ram Murty , Biswajyoti Saha
We study the triple convolution sum of the divisor function given by for where denotes the number of positive divisors of n. Based on some algebraic and geometric considerations, Browning conjectured that the above sum is asymptotic to , for a suitable constant , as . This conjecture is still unproved. Using sieve-theoretic results of Wolke and Nair (respectively), it is possible to derive the exact order of the sum. The lower bound of the correct order of magnitude can also be derived by very elementary arguments. In this article, using the Tauberian theory for multiple Dirichlet series, we prove an explicit lower bound and provide a new theoretical framework to predict Browning's conjectured constant .
{"title":"A triple convolution sum of the divisor function","authors":"Bikram Misra , M. Ram Murty , Biswajyoti Saha","doi":"10.1016/j.jnt.2025.11.014","DOIUrl":"10.1016/j.jnt.2025.11.014","url":null,"abstract":"<div><div>We study the triple convolution sum of the divisor function given by<span><span><span><math><munder><mo>∑</mo><mrow><mi>n</mi><mo>≤</mo><mi>x</mi></mrow></munder><mi>d</mi><mo>(</mo><mi>n</mi><mo>)</mo><mi>d</mi><mo>(</mo><mi>n</mi><mo>−</mo><mi>h</mi><mo>)</mo><mi>d</mi><mo>(</mo><mi>n</mi><mo>+</mo><mi>h</mi><mo>)</mo></math></span></span></span> for <span><math><mi>h</mi><mo>≠</mo><mn>0</mn></math></span> where <span><math><mi>d</mi><mo>(</mo><mi>n</mi><mo>)</mo></math></span> denotes the number of positive divisors of <em>n</em>. Based on some algebraic and geometric considerations, Browning conjectured that the above sum is asymptotic to <span><math><msub><mrow><mi>c</mi></mrow><mrow><mi>h</mi></mrow></msub><mi>x</mi><msup><mrow><mo>(</mo><mi>log</mi><mo></mo><mi>x</mi><mo>)</mo></mrow><mrow><mn>3</mn></mrow></msup></math></span>, for a suitable constant <span><math><msub><mrow><mi>c</mi></mrow><mrow><mi>h</mi></mrow></msub><mo>≠</mo><mn>0</mn></math></span>, as <span><math><mi>x</mi><mo>→</mo><mo>∞</mo></math></span>. This conjecture is still unproved. Using sieve-theoretic results of Wolke and Nair (respectively), it is possible to derive the exact order of the sum. The lower bound of the correct order of magnitude can also be derived by very elementary arguments. In this article, using the Tauberian theory for multiple Dirichlet series, we prove an explicit lower bound and provide a new theoretical framework to predict Browning's conjectured constant <span><math><msub><mrow><mi>c</mi></mrow><mrow><mi>h</mi></mrow></msub></math></span>.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"283 ","pages":"Pages 97-120"},"PeriodicalIF":0.7,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-29DOI: 10.1016/j.jnt.2025.11.013
Mohammad Javaheri
We study the dynamical properties of the semigroup generated by the maps and acting on the positive rational numbers , with a focus on their connection to N-expansions. For , we establish the existence of an infinite subset on which acts transitively: for any , there exists such that . We use this result to show that, for the same values of N, there are infinitely many rational numbers with purely periodic N-expansions of any sufficiently large minimal period.
{"title":"Transitive actions and purely periodic N-expansions","authors":"Mohammad Javaheri","doi":"10.1016/j.jnt.2025.11.013","DOIUrl":"10.1016/j.jnt.2025.11.013","url":null,"abstract":"<div><div>We study the dynamical properties of the semigroup <span><math><mo>〈</mo><mi>f</mi><mo>,</mo><mi>g</mi><mo>〉</mo></math></span> generated by the maps <span><math><mi>f</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>=</mo><mi>x</mi><mo>+</mo><mn>1</mn></math></span> and <span><math><mi>g</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>=</mo><mi>N</mi><mo>/</mo><mi>x</mi></math></span> acting on the positive rational numbers <span><math><msup><mrow><mi>Q</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>, with a focus on their connection to <em>N</em>-expansions. For <span><math><mi>N</mi><mo>∈</mo><mi>N</mi><mo>∖</mo><mo>{</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>,</mo><mn>4</mn><mo>,</mo><mn>6</mn><mo>}</mo></math></span>, we establish the existence of an infinite subset <span><math><mi>A</mi><mo>⊆</mo><msup><mrow><mi>Q</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span> on which <span><math><mo>〈</mo><mi>f</mi><mo>,</mo><mi>g</mi><mo>〉</mo></math></span> acts transitively: for any <span><math><mi>x</mi><mo>,</mo><mi>y</mi><mo>∈</mo><mi>A</mi></math></span>, there exists <span><math><mi>σ</mi><mo>∈</mo><mo>〈</mo><mi>f</mi><mo>,</mo><mi>g</mi><mo>〉</mo></math></span> such that <span><math><mi>y</mi><mo>=</mo><mi>σ</mi><mo>(</mo><mi>x</mi><mo>)</mo></math></span>. We use this result to show that, for the same values of <em>N</em>, there are infinitely many rational numbers with purely periodic <em>N</em>-expansions of any sufficiently large minimal period.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"283 ","pages":"Pages 1-14"},"PeriodicalIF":0.7,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145876998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-29DOI: 10.1016/j.jnt.2025.11.015
Dubi Kelmer
We give an optimal bound for the remainder when counting the number of rational points on the n-dimensional sphere with bounded denominator for any .
对于任意n≥2的n维球面上有界分母有理点的个数,给出了余数的最优界。
{"title":"Counting rational points on the sphere with bounded denominator","authors":"Dubi Kelmer","doi":"10.1016/j.jnt.2025.11.015","DOIUrl":"10.1016/j.jnt.2025.11.015","url":null,"abstract":"<div><div>We give an optimal bound for the remainder when counting the number of rational points on the <em>n</em>-dimensional sphere with bounded denominator for any <span><math><mi>n</mi><mo>≥</mo><mn>2</mn></math></span>.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"282 ","pages":"Pages 174-191"},"PeriodicalIF":0.7,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-29DOI: 10.1016/j.jnt.2025.11.008
Tristan Phillips
Let G be a p-divisible group over a complete discrete valuation ring R of characteristic p. The generic fiber of G determines a Galois representation ρ. The image of ρ admits a ramification filtration and a Lie filtration. We relate these filtrations in the case G is one dimensional, giving an equicharacteristic version of Sen's theorem in this setting. This result generalizes a result of Gross. Additionally, we prove that the representation associated to the étale part of G is irreducible, generalizing a result of Chai.
{"title":"Local monodromy of 1-dimensional p-divisible groups","authors":"Tristan Phillips","doi":"10.1016/j.jnt.2025.11.008","DOIUrl":"10.1016/j.jnt.2025.11.008","url":null,"abstract":"<div><div>Let <em>G</em> be a <em>p</em>-divisible group over a complete discrete valuation ring <em>R</em> of characteristic <em>p</em>. The generic fiber of <em>G</em> determines a Galois representation <em>ρ</em>. The image of <em>ρ</em> admits a ramification filtration and a Lie filtration. We relate these filtrations in the case <em>G</em> is one dimensional, giving an equicharacteristic version of Sen's theorem in this setting. This result generalizes a result of Gross. Additionally, we prove that the representation associated to the étale part of <em>G</em> is irreducible, generalizing a result of Chai.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"283 ","pages":"Pages 259-284"},"PeriodicalIF":0.7,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-29DOI: 10.1016/j.jnt.2025.11.012
Hongyuan Rui , Ce Xu
In this paper, we define extended trigonometric functions via series and employ the method of contour integration to investigate the parity of certain cyclotomic Euler sums and multiple polylogarithm function. We will prove parity results for cyclotomic Euler sums of arbitrary degree, explicit formulas for the parity of cyclotomic linear and quadratic Euler sums, as well as some formulas for the parity of cyclotomic cubic Euler sums and multiple polylogarithms. As a direct corollary, we derive known formulas concerning the parity of classical Euler sums and alternating Euler sums.
{"title":"Contour integrations and parity results of cyclotomic Euler sums and multiple polylogarithm function","authors":"Hongyuan Rui , Ce Xu","doi":"10.1016/j.jnt.2025.11.012","DOIUrl":"10.1016/j.jnt.2025.11.012","url":null,"abstract":"<div><div>In this paper, we define extended trigonometric functions via series and employ the method of contour integration to investigate the parity of certain cyclotomic Euler sums and multiple polylogarithm function. We will prove parity results for cyclotomic Euler sums of arbitrary degree, explicit formulas for the parity of cyclotomic linear and quadratic Euler sums, as well as some formulas for the parity of cyclotomic cubic Euler sums and multiple polylogarithms. As a direct corollary, we derive known formulas concerning the parity of classical Euler sums and alternating Euler sums.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"283 ","pages":"Pages 64-96"},"PeriodicalIF":0.7,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-29DOI: 10.1016/j.jnt.2025.11.009
Alexander Shashkov
<div><div>We study the low lying zeros of <span><math><mi>G</mi><mi>L</mi><mo>(</mo><mn>2</mn><mo>)</mo><mo>×</mo><mi>G</mi><mi>L</mi><mo>(</mo><mn>2</mn><mo>)</mo></math></span> Rankin-Selberg <em>L</em>-functions. Assuming the Generalized Riemann Hypothesis, we compute the 1-level density of the low-lying zeroes of <span><math><mi>L</mi><mo>(</mo><mi>s</mi><mo>,</mo><mi>f</mi><mo>⊗</mo><mi>g</mi><mo>)</mo></math></span> averaged over families of Rankin-Selberg convolutions, where <span><math><mi>f</mi><mo>,</mo><mi>g</mi></math></span> are cuspidal newforms with even weights <span><math><msub><mrow><mi>k</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>k</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> and prime levels <span><math><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, respectively. The Katz-Sarnak density conjecture predicts that in the limit, the 1-level density of suitable families of <em>L</em>-functions is the same as the distribution of eigenvalues of corresponding families of random matrices. The 1-level density relies on a smooth test function <em>ϕ</em> whose Fourier transform <span><math><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></math></span> has compact support. In general, we show the Katz-Sarnak density conjecture holds for test functions <em>ϕ</em> with <span><math><mi>supp</mi><mspace></mspace><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>⊂</mo><mo>(</mo><mo>−</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>,</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>)</mo></math></span>. When <span><math><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, we prove the density conjecture for <span><math><mi>supp</mi><mspace></mspace><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>⊂</mo><mo>(</mo><mo>−</mo><mfrac><mrow><mn>5</mn></mrow><mrow><mn>4</mn></mrow></mfrac><mo>,</mo><mfrac><mrow><mn>5</mn></mrow><mrow><mn>4</mn></mrow></mfrac><mo>)</mo></math></span> when <span><math><msub><mrow><mi>k</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>≠</mo><msub><mrow><mi>k</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <span><math><mi>supp</mi><mspace></mspace><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>⊂</mo><mo>(</mo><mo>−</mo><mfrac><mrow><mn>29</mn></mrow><mrow><mn>28</mn></mrow></mfrac><mo>,</mo><mfrac><mrow><mn>29</mn></mrow><mrow><mn>28</mn></mrow></mfrac><mo>)</mo></math></span> when <span><math><msub><mrow><mi>k</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><msub><mrow><mi>k</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. A secondary term contributes to the 1-level density when the support of <span><math><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></math></span> ex
我们研究了GL(2)×GL(2) Rankin-Selberg l -函数的低洼零点。假设广义黎曼假设,我们计算了L(s,f⊗g)在Rankin-Selberg卷积族上平均的低零的1能级密度,其中f,g分别是偶数权值k1,k2和素数阶N1,N2的反转新形式。根据Katz-Sarnak密度猜想,在极限情况下,l -函数的合适族的1级密度与随机矩阵的相应族的特征值分布相同。1级密度依赖于平滑测试函数φ,其傅里叶变换φ具有紧凑的支持。一般来说,我们用supppφ φ φ(−12,12)证明了测试函数φ的Katz-Sarnak密度猜想成立。当N1=N2时,我们证明了k1≠k2时,supϕ´´(−54,54)和k1=k2时,supϕ´´(−2928,2928)的密度猜想。当φ -的支持度超过(−1,1)时,二级项有助于1级密度,这使得这些结果特别有趣。使我们能够将φ -的支持扩展到(- 1,1)以外的主要思想是对由Petersson公式产生的Kloosterman和的乘积的分析。在k1=k2的情况下,我们也仔细地处理了极点的贡献。我们的工作提供了在中心点不消失的Rankin-Selberg l -函数比例的条件下界,以及Keating和Snaith关于中心l值的一个相关猜想。
{"title":"Low lying zeros of Rankin-Selberg L-functions","authors":"Alexander Shashkov","doi":"10.1016/j.jnt.2025.11.009","DOIUrl":"10.1016/j.jnt.2025.11.009","url":null,"abstract":"<div><div>We study the low lying zeros of <span><math><mi>G</mi><mi>L</mi><mo>(</mo><mn>2</mn><mo>)</mo><mo>×</mo><mi>G</mi><mi>L</mi><mo>(</mo><mn>2</mn><mo>)</mo></math></span> Rankin-Selberg <em>L</em>-functions. Assuming the Generalized Riemann Hypothesis, we compute the 1-level density of the low-lying zeroes of <span><math><mi>L</mi><mo>(</mo><mi>s</mi><mo>,</mo><mi>f</mi><mo>⊗</mo><mi>g</mi><mo>)</mo></math></span> averaged over families of Rankin-Selberg convolutions, where <span><math><mi>f</mi><mo>,</mo><mi>g</mi></math></span> are cuspidal newforms with even weights <span><math><msub><mrow><mi>k</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>k</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> and prime levels <span><math><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, respectively. The Katz-Sarnak density conjecture predicts that in the limit, the 1-level density of suitable families of <em>L</em>-functions is the same as the distribution of eigenvalues of corresponding families of random matrices. The 1-level density relies on a smooth test function <em>ϕ</em> whose Fourier transform <span><math><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></math></span> has compact support. In general, we show the Katz-Sarnak density conjecture holds for test functions <em>ϕ</em> with <span><math><mi>supp</mi><mspace></mspace><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>⊂</mo><mo>(</mo><mo>−</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>,</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>)</mo></math></span>. When <span><math><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, we prove the density conjecture for <span><math><mi>supp</mi><mspace></mspace><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>⊂</mo><mo>(</mo><mo>−</mo><mfrac><mrow><mn>5</mn></mrow><mrow><mn>4</mn></mrow></mfrac><mo>,</mo><mfrac><mrow><mn>5</mn></mrow><mrow><mn>4</mn></mrow></mfrac><mo>)</mo></math></span> when <span><math><msub><mrow><mi>k</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>≠</mo><msub><mrow><mi>k</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <span><math><mi>supp</mi><mspace></mspace><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>⊂</mo><mo>(</mo><mo>−</mo><mfrac><mrow><mn>29</mn></mrow><mrow><mn>28</mn></mrow></mfrac><mo>,</mo><mfrac><mrow><mn>29</mn></mrow><mrow><mn>28</mn></mrow></mfrac><mo>)</mo></math></span> when <span><math><msub><mrow><mi>k</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><msub><mrow><mi>k</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. A secondary term contributes to the 1-level density when the support of <span><math><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></math></span> ex","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"283 ","pages":"Pages 170-215"},"PeriodicalIF":0.7,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.jnt.2025.11.002
Joaquim Cera Da Conceição
{"title":"Corrigendum to “Divisibility of the multiplicative order modulo monic irreducible polynomials over finite fields” [J. Number Theory 277 (2025) 105–123]","authors":"Joaquim Cera Da Conceição","doi":"10.1016/j.jnt.2025.11.002","DOIUrl":"10.1016/j.jnt.2025.11.002","url":null,"abstract":"","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"282 ","pages":"Pages 144-146"},"PeriodicalIF":0.7,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-09DOI: 10.1016/j.jnt.2025.11.006
Zhe Cao , Harold Erazo , Carlos Gustavo Moreira
Text
For , let denote the set of such that has only finitely many rational solutions . It is a classical fact, known since the 1950s, that is uncountable for and countable for . However, the cardinality of does not appear to be present in the literature. We prove that is uncountable.
More generally, we show that for any , the set of with Lagrange value exactly 3 and such that has exactly n rational solutions is also uncountable.
Video
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{"title":"On irrationals with Lagrange value exactly 3","authors":"Zhe Cao , Harold Erazo , Carlos Gustavo Moreira","doi":"10.1016/j.jnt.2025.11.006","DOIUrl":"10.1016/j.jnt.2025.11.006","url":null,"abstract":"<div><h3>Text</h3><div>For <span><math><mi>c</mi><mo>></mo><mn>0</mn></math></span>, let <span><math><msub><mrow><mi>X</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> denote the set of <span><math><mi>x</mi><mo>∈</mo><mi>R</mi><mo>﹨</mo><mi>Q</mi></math></span> such that <span><math><mrow><mo>|</mo><mi>x</mi><mo>−</mo><mfrac><mrow><mi>p</mi></mrow><mrow><mi>q</mi></mrow></mfrac><mo>|</mo></mrow><mo><</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mi>c</mi><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfrac></math></span> has only finitely many rational solutions <span><math><mfrac><mrow><mi>p</mi></mrow><mrow><mi>q</mi></mrow></mfrac></math></span>. It is a classical fact, known since the 1950s, that <span><math><msub><mrow><mi>X</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> is uncountable for <span><math><mi>c</mi><mo>></mo><mn>3</mn></math></span> and countable for <span><math><mi>c</mi><mo><</mo><mn>3</mn></math></span>. However, the cardinality of <span><math><msub><mrow><mi>X</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> does not appear to be present in the literature. We prove that <span><math><msub><mrow><mi>X</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> is uncountable.</div><div>More generally, we show that for any <span><math><mi>n</mi><mo>∈</mo><mi>N</mi><mo>∪</mo><mo>{</mo><mo>∞</mo><mo>}</mo></math></span>, the set of <span><math><mi>x</mi><mo>∈</mo><mi>R</mi><mo>﹨</mo><mi>Q</mi></math></span> with Lagrange value exactly 3 and such that <span><math><mrow><mo>|</mo><mi>x</mi><mo>−</mo><mfrac><mrow><mi>p</mi></mrow><mrow><mi>q</mi></mrow></mfrac><mo>|</mo></mrow><mo><</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>3</mn><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfrac></math></span> has exactly <em>n</em> rational solutions <span><math><mfrac><mrow><mi>p</mi></mrow><mrow><mi>q</mi></mrow></mfrac></math></span> is also uncountable.</div></div><div><h3>Video</h3><div>For a video summary of this paper, please visit <span><span>https://youtu.be/VyKB99-kVeY</span><svg><path></path></svg></span>.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"282 ","pages":"Pages 147-173"},"PeriodicalIF":0.7,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-05DOI: 10.1016/j.jnt.2025.11.001
Ruben Hambardzumyan , Mihran Papikian
Let be a monic polynomial whose roots are distinct integers. We study the ideal class monoid and the ideal class group of the ring . We obtain formulas for the orders of these objects, and study their asymptotic behavior as the discriminant of tends to infinity, in analogy with the Brauer-Siegel theorem. Finally, we describe the structure of the ideal class group when the degree of is 2 or 3.
{"title":"On ideal class groups of totally degenerate number rings","authors":"Ruben Hambardzumyan , Mihran Papikian","doi":"10.1016/j.jnt.2025.11.001","DOIUrl":"10.1016/j.jnt.2025.11.001","url":null,"abstract":"<div><div>Let <span><math><mi>χ</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>∈</mo><mi>Z</mi><mo>[</mo><mi>x</mi><mo>]</mo></math></span> be a monic polynomial whose roots are distinct integers. We study the ideal class monoid and the ideal class group of the ring <span><math><mi>Z</mi><mo>[</mo><mi>x</mi><mo>]</mo><mo>/</mo><mo>(</mo><mi>χ</mi><mo>(</mo><mi>x</mi><mo>)</mo><mo>)</mo></math></span>. We obtain formulas for the orders of these objects, and study their asymptotic behavior as the discriminant of <span><math><mi>χ</mi><mo>(</mo><mi>x</mi><mo>)</mo></math></span> tends to infinity, in analogy with the Brauer-Siegel theorem. Finally, we describe the structure of the ideal class group when the degree of <span><math><mi>χ</mi><mo>(</mo><mi>x</mi><mo>)</mo></math></span> is 2 or 3.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"282 ","pages":"Pages 118-143"},"PeriodicalIF":0.7,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-03DOI: 10.1016/j.jnt.2025.11.003
Mingkuan Zhang , Yichao Zhang
We prove that if ν has small norm with respect to the level and the weight, the ν-th Hilbert Poincaré series does not vanish identically. We also prove Selberg's identity on Kloosterman sums in the case of number fields, which implies certain vanishing and non-vanishing relations of Hilbert Poincaré series when the narrow class number is 1. Finally, we pass to the adelic setting and interpret the problem via Hecke operators.
{"title":"On the non-vanishing of Hilbert Poincaré series","authors":"Mingkuan Zhang , Yichao Zhang","doi":"10.1016/j.jnt.2025.11.003","DOIUrl":"10.1016/j.jnt.2025.11.003","url":null,"abstract":"<div><div>We prove that if <em>ν</em> has small norm with respect to the level and the weight, the <em>ν</em>-th Hilbert Poincaré series does not vanish identically. We also prove Selberg's identity on Kloosterman sums in the case of number fields, which implies certain vanishing and non-vanishing relations of Hilbert Poincaré series when the narrow class number is 1. Finally, we pass to the adelic setting and interpret the problem via Hecke operators.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"282 ","pages":"Pages 31-47"},"PeriodicalIF":0.7,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}