{"title":"The sharp threshold for rainbow stackings of random edge-colourings","authors":"Hong Liu, Guorui Ma, Yangrui Xiang, Zhifei Yan","doi":"10.1112/blms.70522","DOIUrl":null,"url":null,"abstract":"<p>A rainbow stacking of <span></span><math>\n <semantics>\n <mi>m</mi>\n <annotation>$m$</annotation>\n </semantics></math> independent, uniformly random <span></span><math>\n <semantics>\n <mi>r</mi>\n <annotation>$r$</annotation>\n </semantics></math>-edge-colourings of <span></span><math>\n <semantics>\n <msub>\n <mi>K</mi>\n <mi>n</mi>\n </msub>\n <annotation>$K_n$</annotation>\n </semantics></math> is a tuple of vertex permutations that superimposes the colourings such that no two edges of the same colour overlap. The study of the critical palette size <span></span><math>\n <semantics>\n <mi>r</mi>\n <annotation>$r$</annotation>\n </semantics></math> required for the existence of such stackings was recently initiated by Alon, Defant and Kravitz (<i>Bull. Lond. Math. Soc</i>. 57 (2025), 1656–1670), who bounded the phase transition within a constant-order window around <span></span><math>\n <semantics>\n <mfrac>\n <mrow>\n <mi>m</mi>\n <mfenced>\n <mfrac>\n <mi>n</mi>\n <mn>2</mn>\n </mfrac>\n </mfenced>\n </mrow>\n <mrow>\n <mn>2</mn>\n <mi>log</mi>\n <mo>(</mo>\n <mi>n</mi>\n <mo>!</mo>\n <mo>)</mo>\n </mrow>\n </mfrac>\n <annotation>$\\frac{m\\binom{n}{2}}{2\\log (n!)}$</annotation>\n </semantics></math>. We determine the constant term in this transition. For every fixed <span></span><math>\n <semantics>\n <mrow>\n <mi>m</mi>\n <mo>⩾</mo>\n <mn>2</mn>\n </mrow>\n <annotation>$m\\geqslant 2$</annotation>\n </semantics></math> and every function <span></span><math>\n <semantics>\n <mrow>\n <mi>ω</mi>\n <mo>(</mo>\n <mi>n</mi>\n <mo>)</mo>\n <mo>→</mo>\n <mi>∞</mi>\n </mrow>\n <annotation>$\\omega (n)\\rightarrow \\infty$</annotation>\n </semantics></math>, with high probability there is no rainbow stacking if\n\n </p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"58 10","pages":""},"PeriodicalIF":1.0000,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin of the London Mathematical Society","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1112/blms.70522","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
A rainbow stacking of independent, uniformly random -edge-colourings of is a tuple of vertex permutations that superimposes the colourings such that no two edges of the same colour overlap. The study of the critical palette size required for the existence of such stackings was recently initiated by Alon, Defant and Kravitz (Bull. Lond. Math. Soc. 57 (2025), 1656–1670), who bounded the phase transition within a constant-order window around . We determine the constant term in this transition. For every fixed and every function , with high probability there is no rainbow stacking if