Annals of Combinatorics最新文献

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Long Twins in Random Words 随机词中的长双胞胎
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-05-23 DOI: 10.1007/s00026-023-00651-5
Andrzej Dudek, Jarosław Grytczuk, Andrzej Ruciński
{"title":"Long Twins in Random Words","authors":"Andrzej Dudek,&nbsp;Jarosław Grytczuk,&nbsp;Andrzej Ruciński","doi":"10.1007/s00026-023-00651-5","DOIUrl":"10.1007/s00026-023-00651-5","url":null,"abstract":"<div><p><i>Twins</i> in a finite word are formed by a pair of identical subwords placed at disjoint sets of positions. We investigate the maximum length of twins in <i>a random</i> word over a <i>k</i>-letter alphabet. The obtained lower bounds for small values of <i>k</i> significantly improve the best estimates known in the deterministic case. Bukh and Zhou in 2016 showed that every ternary word of length <i>n</i> contains twins of length at least 0.34<i>n</i>. Our main result states that in a random ternary word of length <i>n</i>, with high probability, one can find twins of length at least 0.41<i>n</i>. In the general case of alphabets of size <span>(kgeqslant 3)</span> we obtain analogous lower bounds of the form <span>(frac{1.64}{k+1}n)</span> which are better than the known deterministic bounds for <span>(kleqslant 354)</span>. In addition, we present similar results for <i>multiple</i> twins in random words.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00651-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46164776","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}
引用次数: 1
On the Subdivision Algebra for the Polytope $$mathcal {U}_{I,overline{J}}$$ 关于多项式$$mathcal的细分代数{U}_{I,overline{J}}$$
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-05-19 DOI: 10.1007/s00026-023-00650-6
Matias von Bell, Martha Yip
{"title":"On the Subdivision Algebra for the Polytope $$mathcal {U}_{I,overline{J}}$$","authors":"Matias von Bell, Martha Yip","doi":"10.1007/s00026-023-00650-6","DOIUrl":"https://doi.org/10.1007/s00026-023-00650-6","url":null,"abstract":"","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45728539","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}
引用次数: 0
Refined Enumeration of $${{varvec{k}}}$$ k -plane Trees and  $${varvec{k}}$$ 改进了$${{varvec{k}}}$$ k -平面树的枚举方法 $${varvec{k}}$$
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-05-10 DOI: 10.1007/s00026-023-00642-6
I. Okoth, S. Wagner
{"title":"Refined Enumeration of \u0000 \u0000 \u0000 \u0000 $${{varvec{k}}}$$\u0000 \u0000 \u0000 k\u0000 \u0000 \u0000 -plane Trees and \u0000 \u0000 \u0000 \u0000 $${varvec{k}}$$\u0000 \u0000 \u0000 ","authors":"I. Okoth, S. Wagner","doi":"10.1007/s00026-023-00642-6","DOIUrl":"https://doi.org/10.1007/s00026-023-00642-6","url":null,"abstract":"","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41390405","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}
引用次数: 0
The Rank of the Sandpile Group of Random Directed Bipartite Graphs 随机有向二部图的沙堆群的秩
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-04-28 DOI: 10.1007/s00026-023-00637-3
Atal Bhargava, Jack DePascale, Jake Koenig
{"title":"The Rank of the Sandpile Group of Random Directed Bipartite Graphs","authors":"Atal Bhargava,&nbsp;Jack DePascale,&nbsp;Jake Koenig","doi":"10.1007/s00026-023-00637-3","DOIUrl":"10.1007/s00026-023-00637-3","url":null,"abstract":"<div><p>We identify the asymptotic distribution of <i>p</i>-rank of the sandpile group of random directed bipartite graphs which are not too imbalanced. We show this matches exactly with that of the Erdös–Rényi random directed graph model, suggesting that the Sylow <i>p</i>-subgroups of this model may also be Cohen–Lenstra distributed. Our work builds on the results of Koplewitz who studied <i>p</i>-rank distributions for unbalanced random bipartite graphs, and showed that for sufficiently unbalanced graphs, the distribution of <i>p</i>-rank differs from the Cohen–Lenstra distribution. Koplewitz (sandpile groups of random bipartite graphs, https://arxiv.org/abs/1705.07519, 2017) conjectured that for random balanced bipartite graphs, the expected value of <i>p</i>-rank is <i>O</i>(1) for any <i>p</i>. This work proves his conjecture and gives the exact distribution for the subclass of directed graphs.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00637-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46156088","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}
引用次数: 1
Congruence Modulo 4 for Andrews’ Even Parts Below Odd Parts Partition Function 奇部配分函数下Andrews偶部的同余模4
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-03-29 DOI: 10.1007/s00026-023-00645-3
Dandan Chen, Rong Chen
{"title":"Congruence Modulo 4 for Andrews’ Even Parts Below Odd Parts Partition Function","authors":"Dandan Chen,&nbsp;Rong Chen","doi":"10.1007/s00026-023-00645-3","DOIUrl":"10.1007/s00026-023-00645-3","url":null,"abstract":"<div><p>We find and prove a class of congruences modulo 4 for Andrews’ partition with certain ternary quadratic form. We also discuss distribution of <span>(overline{mathcal{E}mathcal{O}}(n))</span> and further prove that <span>(overline{mathcal{E}mathcal{O}}(n)equiv 0pmod 4)</span> for almost all <i>n</i>. This study was inspired by similar congruences modulo 4 in the work by the second author and Garvan.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44237044","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}
引用次数: 2
Embedding Dimensions of Simplicial Complexes on Few Vertices 少量点上简单复合体的嵌入维数
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-03-28 DOI: 10.1007/s00026-023-00644-4
Florian Frick, Mirabel Hu, Verity Scheel, Steven Simon
{"title":"Embedding Dimensions of Simplicial Complexes on Few Vertices","authors":"Florian Frick,&nbsp;Mirabel Hu,&nbsp;Verity Scheel,&nbsp;Steven Simon","doi":"10.1007/s00026-023-00644-4","DOIUrl":"10.1007/s00026-023-00644-4","url":null,"abstract":"<div><p>We provide a simple characterization of simplicial complexes on few vertices that embed into the <i>d</i>-sphere. Namely, a simplicial complex on <span>(d+3)</span> vertices embeds into the <i>d</i>-sphere if and only if its non-faces do not form an intersecting family. As immediate consequences, we recover the classical van Kampen–Flores theorem and provide a topological extension of the Erdős–Ko–Rado theorem. By analogy with Fáry’s theorem for planar graphs, we show in addition that such complexes satisfy the rigidity property that continuous and linear embeddability are equivalent.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00644-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41826685","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}
引用次数: 3
Strict Log-Subadditivity for Overpartition Rank 过分割秩的严格对数子可加性
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-03-24 DOI: 10.1007/s00026-023-00643-5
Helen W. J. Zhang, Ying Zhong
{"title":"Strict Log-Subadditivity for Overpartition Rank","authors":"Helen W. J. Zhang,&nbsp;Ying Zhong","doi":"10.1007/s00026-023-00643-5","DOIUrl":"10.1007/s00026-023-00643-5","url":null,"abstract":"<div><p>Bessenrodt and Ono initially found the strict log-subadditivity of partition function <i>p</i>(<i>n</i>), that is, <span>(p(a+b)&lt; p(a)p(b))</span> for <span>(a,b&gt;1)</span> and <span>(a+b&gt;9)</span>. Many other important partition statistics are proved to enjoy similar properties. Lovejoy introduced the overpartition rank as an analog of Dyson’s rank for partitions from the <i>q</i>-series perspective. Let <span>({overline{N}}(a,c,n))</span> denote the number of overpartitions with rank congruent to <i>a</i> modulo <i>c</i>. Ciolan computed the asymptotic formula of <span>({overline{N}}(a,c,n))</span> and showed that <span>({overline{N}}(a, c, n) &gt; {overline{N}}(b, c, n))</span> for <span>(0le a&lt;ble lfloor frac{c}{2}rfloor )</span> and <i>n</i> large enough if <span>(cge 7)</span>. In this paper, we derive an upper bound and a lower bound of <span>({overline{N}}(a,c,n))</span> for each <span>(cge 3)</span> by using the asymptotics due to Ciolan. Consequently, we establish the strict log-subadditivity of <span>({overline{N}}(a,c,n))</span> analogous to the partition function <i>p</i>(<i>n</i>).</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46460253","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}
引用次数: 1
Dominance Regions for Rank Two Cluster Algebras 秩二簇代数的优势域
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-03-20 DOI: 10.1007/s00026-023-00636-4
Dylan Rupel, Salvatore Stella
{"title":"Dominance Regions for Rank Two Cluster Algebras","authors":"Dylan Rupel,&nbsp;Salvatore Stella","doi":"10.1007/s00026-023-00636-4","DOIUrl":"10.1007/s00026-023-00636-4","url":null,"abstract":"<div><p>We study the polygons defining the dominance order on <span>({varvec{g}})</span>-vectors in cluster algebras of rank 2 as in Fig. 1.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00636-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48224641","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}
引用次数: 0
Berkovich–Uncu Type Partition Inequalities Concerning Impermissible Sets and Perfect Power Frequencies 关于不可容许集和完全工频的Berkovich–Uncu型划分不等式
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-03-16 DOI: 10.1007/s00026-023-00638-2
Damanvir Singh Binner, Neha Gupta, Manoj Upreti
{"title":"Berkovich–Uncu Type Partition Inequalities Concerning Impermissible Sets and Perfect Power Frequencies","authors":"Damanvir Singh Binner,&nbsp;Neha Gupta,&nbsp;Manoj Upreti","doi":"10.1007/s00026-023-00638-2","DOIUrl":"10.1007/s00026-023-00638-2","url":null,"abstract":"<div><p>Recently, Rattan and the first author (Ann. Comb. 25 (2021) 697–728) proved a conjectured inequality of Berkovich and Uncu (Ann. Comb. 23 (2019) 263–284) concerning partitions with an impermissible part. In this article, we generalize this inequality upon considering <i>t</i> impermissible parts. We compare these with partitions whose certain parts appear with a frequency which is a perfect <span>(t^{th})</span> power. In addition, the partitions that we study here have smallest part greater than or equal to <i>s</i> for some given natural number <i>s</i>. Our inequalities hold after a certain bound, which for given <i>t</i> is a polynomial in <i>s</i>, a major improvement over the previously known bound in the case <span>(t=1)</span>. To prove these inequalities, our methods involve constructing injective maps between the relevant sets of partitions. The construction of these maps crucially involves concepts from analysis and calculus, such as explicit maps used to prove countability of <span>(mathbb {N}^t)</span>, and Jensen’s inequality for convex functions, and then merge them with techniques from number theory such as Frobenius numbers, congruence classes, binary numbers and quadratic residues. We also show a connection of our results to colored partitions. Finally, we pose an open problem which seems to be related to power residues and the almost universality of diagonal ternary quadratic forms.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00638-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42684461","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}
引用次数: 0
Lattice Paths and Negatively Indexed Weight-Dependent Binomial Coefficients 格路径与负索引权相关二项式系数
IF 0.5 4区 数学
Annals of Combinatorics Pub Date : 2023-02-21 DOI: 10.1007/s00026-023-00639-1
Josef Küstner, Michael J. Schlosser, Meesue Yoo
{"title":"Lattice Paths and Negatively Indexed Weight-Dependent Binomial Coefficients","authors":"Josef Küstner,&nbsp;Michael J. Schlosser,&nbsp;Meesue Yoo","doi":"10.1007/s00026-023-00639-1","DOIUrl":"10.1007/s00026-023-00639-1","url":null,"abstract":"<div><p>In 1992, Loeb (Adv Math, 91:64–74, 1992) considered a natural extension of the binomial coefficients to negative entries and gave a combinatorial interpretation in terms of hybrid sets. He showed that many of the fundamental properties of binomial coefficients continue to hold in this extended setting. Recently, Formichella and Straub (Ann Comb, 23:725–748, 2019) showed that these results can be extended to the <i>q</i>-binomial coefficients with arbitrary integer values and extended the work of Loeb further by examining the arithmetic properties of the <i>q</i>-binomial coefficients. In this paper, we give an alternative combinatorial interpretation in terms of lattice paths and consider an extension of the more general weight-dependent binomial coefficients, first defined by Schlosser (Sém Lothar Combin, 81:24, 2020), to arbitrary integer values. Remarkably, many of the results of Loeb, Formichella and Straub continue to hold in the general weighted setting. We also examine important special cases of the weight-dependent binomial coefficients, including ordinary, <i>q</i>- and elliptic binomial coefficients as well as elementary and complete homogeneous symmetric functions.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00639-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50501781","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}
引用次数: 0
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