{"title":"Correction to: The Likely Maximum Size of Twin Subtrees in a Large Random Tree","authors":"Miklós Bóna, Ovidiu Costin, Boris Pittel","doi":"10.1007/s00026-025-00761-2","DOIUrl":"10.1007/s00026-025-00761-2","url":null,"abstract":"","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"945 - 946"},"PeriodicalIF":0.7,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Equitable and List Equitable Colorings of Planar Graphs Without 5-Cycles","authors":"Aijun Dong, Wenwen Zhang","doi":"10.1007/s00026-025-00748-z","DOIUrl":"10.1007/s00026-025-00748-z","url":null,"abstract":"<div><p>A graph <i>G</i> is <i>k</i> list equitably colorable, if for any given <i>k</i>-uniform list assignment <i>L</i>, <i>G</i> is <i>L</i>-colorable and each color appears on at most <span>(lceil frac{|V(G)|}{k}rceil )</span> vertices. Kostochka et al. conjectured that if <i>G</i> is a connected graph with maximum degree at least 3, then <i>G</i> is <span>(Delta (G))</span> list equitably colorable, unless <i>G</i> is a complete graph or is <span>(K_{k,k})</span> for some odd <i>k</i>. An equitable <i>k</i>-coloring <i>c</i> of <i>G</i> is a mapping <i>c</i> from <i>V</i>(<i>G</i>) to <span>([k]={1,2,ldots ,k})</span> such that <span>(c(u)ne c(v))</span> for each <span>(uvin E(G))</span>, and for each <span>(k_i)</span>, <span>(k_j in [k])</span>, <span>(||{v|c(v)=k_i}|-|{w|c(w)=k_j}||le 1)</span>. Chen et al. conjectured that each connected graph with maximum degree <span>(Delta )</span> that is different from the complete graph <span>(K_{Delta +1})</span>, the complete bipartite graph <span>(K_{Delta , Delta })</span> and an odd cycle admits an equitable coloring with <span>(Delta )</span> colors. In this paper, we prove that if <i>G</i> is a planar graph without 5-cycles, then <i>G</i> is <i>k</i> list equitably colorable and equitably <i>k</i>-colorable where <span>(kge max {Delta (G),7})</span>.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"637 - 656"},"PeriodicalIF":0.7,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Genus Polynomials of Cubic Graphs with Non-real Roots","authors":"MacKenzie Carr, Varpreet Dhaliwal, Bojan Mohar","doi":"10.1007/s00026-025-00754-1","DOIUrl":"10.1007/s00026-025-00754-1","url":null,"abstract":"<div><p>Given a graph <i>G</i>, its genus polynomial is <span>(Gamma _G(x) = sum _{kge 0} g_k(G)x^k)</span>, where <span>(g_k(G))</span> is the number of two-cell embeddings of <i>G</i> in an orientable surface of genus <i>k</i>. The Log-Concavity Genus Distribution (LCGD) Conjecture states that the genus polynomial of every graph is log-concave. It was further conjectured by Stahl that the genus polynomial of every graph has only real roots, however, this was later disproved. We identify several examples of cubic graphs whose genus polynomials, in addition to having at least one non-real root, have a quadratic factor that is non-log-concave when factored over the real numbers.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"885 - 892"},"PeriodicalIF":0.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mixing on Generalized Associahedra","authors":"William Chang, Colin Defant, Daniel Frishberg","doi":"10.1007/s00026-025-00750-5","DOIUrl":"10.1007/s00026-025-00750-5","url":null,"abstract":"<div><p>Eppstein and Frishberg recently proved that the mixing time for the simple random walk on the 1-skeleton of the associahedron is <span>(O(n^3log ^3 n))</span>. We obtain similar rapid mixing results for the simple random walks on the 1-skeleta of the type-<i>B</i> and type-<i>D</i> associahedra. We adapt Eppstein and Frishberg’s technique to obtain the same bound of <span>(O(n^3log ^3 n))</span> in type <i>B</i> and a bound of <span>(O(n^{13} log ^2 n))</span> in type <i>D</i>; in the process, we establish an expansion bound that is tight up to logarithmic factors in type <i>B</i>.\u0000</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"921 - 943"},"PeriodicalIF":0.7,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Correction to: Positivity Among P-Partition Generating Functions","authors":"Nathan R. T. Lesnevich, Peter R. W. McNamara","doi":"10.1007/s00026-025-00744-3","DOIUrl":"10.1007/s00026-025-00744-3","url":null,"abstract":"<div><p>We correct a theorem on caterpillar posets in Lesnevich and McNamara (Ann Comb 26(1):171–204, 2022). In strengthening the hypotheses on the caterpillar posets we consider, we are also able to strengthen the conclusion on the types of positivity that result.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"947 - 953"},"PeriodicalIF":0.7,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-025-00744-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Minimum Quantum Degrees with Maya Diagrams","authors":"Ryan M. Shifler","doi":"10.1007/s00026-025-00749-y","DOIUrl":"10.1007/s00026-025-00749-y","url":null,"abstract":"<div><p>We use Maya diagrams to refine the criterion by Fulton and Woodward for the smallest powers of the quantum parameter <i>q</i> that occur in a product of Schubert classes in the (small) quantum cohomology of partial flags. Our approach using Maya diagrams yields a combinatorial proof that the minimal quantum degrees are unique for partial flags. Furthermore, visual combinatorial rules are given to perform precise calculations.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 2","pages":"395 - 413"},"PeriodicalIF":0.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145162467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Bubble Lattices II: Combinatorics","authors":"Thomas McConville, Henri Mühle","doi":"10.1007/s00026-025-00743-4","DOIUrl":"10.1007/s00026-025-00743-4","url":null,"abstract":"<div><p>We introduce two simplicial complexes, the noncrossing matching complex and the noncrossing bipartite complex. Both complexes are intimately related to the bubble lattice introduced in our earlier article “Bubble Lattices I: Structure” (arXiv:2202.02874). We study these complexes from both an enumerative and a topological point of view. In particular, we prove that these complexes are shellable and give explicit formulas for certain refined face numbers. Lastly, we conjecture an intriguing connection of these refined face numbers to the so-called <i>M</i>-triangle of the shuffle lattice.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"657 - 690"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Connectivity of Friends-and-Strangers Graphs on Complete Multipartite Graphs","authors":"Honglin Zhu","doi":"10.1007/s00026-024-00740-z","DOIUrl":"10.1007/s00026-024-00740-z","url":null,"abstract":"<div><p>For simple graphs <i>X</i> and <i>Y</i> on <i>n</i> vertices, the friends-and-strangers graph <span>(textsf{FS}(X,Y))</span> is the graph whose vertex set consists of all bijections <span>(sigma : V(X) rightarrow V(Y))</span>, where two bijections <span>(sigma )</span> and <span>(sigma ')</span> are adjacent if and only if they agree on all but two adjacent vertices <span>(a, b in V(X))</span> such that <span>(sigma (a), sigma (b) in V(Y))</span> are adjacent in <i>Y</i>. Resolving a conjecture of Wang, Lu, and Chen, we completely characterize the connectedness of <span>(textsf{FS}(X, Y))</span> when <i>Y</i> is a complete bipartite graph. We further extend this result to when <i>Y</i> is a complete multipartite graph. We also determine when <span>(textsf{FS}(X, Y))</span> has exactly two connected components where <i>X</i> is bipartite and <i>Y</i> is a complete bipartite graph.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"691 - 718"},"PeriodicalIF":0.7,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Completing the Asymptotic Classification of Mostly Symmetric Short Step Walks in an Orthant","authors":"Alexander Kroitor, Stephen Melczer","doi":"10.1007/s00026-024-00739-6","DOIUrl":"10.1007/s00026-024-00739-6","url":null,"abstract":"<div><p>In recent years, the techniques of analytic combinatorics in several variables (ACSV) have been applied to determine asymptotics for several families of lattice path models restricted to the orthant <span>({mathbb {N}}^d)</span> and defined by step sets <span>({mathcal {S}}subset {-1,0,1}^dsetminus {textbf{0}})</span>. Using the theory of ACSV for smooth singular sets, Melczer and Mishna determined asymptotics for the number of walks in any model whose set of steps <span>({mathcal {S}})</span> is ‘highly symmetric’ (symmetric over every axis). Building on this work, Melczer and Wilson determined asymptotics for all models where <span>({mathcal {S}})</span> is ‘mostly symmetric’ (symmetric over all but one axis) <i>except</i> for models whose set of steps have a vector sum of zero but are not highly symmetric. In this paper, we complete the asymptotic classification of the mostly symmetric case by analyzing a family of saddle-point-like integrals whose amplitudes are singular near their saddle points.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 2","pages":"575 - 599"},"PeriodicalIF":0.7,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145167193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Local Limit Theorems for Hook Lengths in Partitions","authors":"Tapas Bhowmik, Wei-Lun Tsai","doi":"10.1007/s00026-024-00737-8","DOIUrl":"10.1007/s00026-024-00737-8","url":null,"abstract":"<div><p>Partition hook lengths have wide-ranging applications in combinatorics, number theory, physics, and representation theory. We study two infinite families of random variables associated with <i>t</i>-hooks. For fixed <span>(tge 1,)</span> if <span>(Y_{t;,n})</span> counts the number of hooks of length <i>t</i> in a random integer partition of <i>n</i>, we prove a uniform local limit theorem for <span>(Y_{t;,n})</span> on any bounded set of <span>({mathbb {R}}.)</span> To achieve this, we establish an asymptotic formula with a power-saving error term for the number of partitions of <i>n</i> with <i>m</i> many <i>t</i>-hooks. In contrast, we define <span>({widehat{Y}}_{t;,n})</span> as the count of hooks divisible by <i>t</i> in a randomly chosen partition of <i>n</i>. While <span>({widehat{Y}}_{t;,n})</span> converges in distribution, we show that it fails to satisfy the local limit theorem for any <span>(t ge 2)</span>. The proofs employ the multivariable saddle-point method, asymptotic formulas for the number of <i>t</i>-core partitions from Anderson and Lulov–Pittel, and estimates of certain exponential sums. Notably, for <span>(t=4,)</span> the analysis involves the asymptotic behavior of class numbers of imaginary quadratic fields.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":"29 3","pages":"853 - 884"},"PeriodicalIF":0.7,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-024-00737-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}