Archit Agarwal, Subhash Chand Bhoria, Pramod Eyyunni, Bibekananda Maji
{"title":"Bressoud–Subbarao Type Weighted Partition Identities for a Generalized Divisor Function","authors":"Archit Agarwal, Subhash Chand Bhoria, Pramod Eyyunni, Bibekananda Maji","doi":"10.1007/s00026-023-00647-1","DOIUrl":"10.1007/s00026-023-00647-1","url":null,"abstract":"<div><p>In 1984, Bressoud and Subbarao obtained an interesting weighted partition identity for a generalized divisor function, by means of combinatorial arguments. Recently, the last three named authors found an analytic proof of the aforementioned identity of Bressoud and Subbarao starting from a <i>q</i>-series identity of Ramanujan. In the present paper, we revisit the combinatorial arguments of Bressoud and Subbarao, and derive a more general weighted partition identity. Furthermore, with the help of a fractional differential operator, we establish a few more Bressoud–Subbarao type weighted partition identities beginning from an identity of Andrews, Garvan and Liang. We also found a one-variable generalization of an identity of Uchimura related to Bell polynomials.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49518651","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":"Congruence Modulo 4 for Andrews’ Even Parts Below Odd Parts Partition Function","authors":"Dandan Chen, 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}
Florian Frick, Mirabel Hu, Verity Scheel, Steven Simon
{"title":"Embedding Dimensions of Simplicial Complexes on Few Vertices","authors":"Florian Frick, Mirabel Hu, Verity Scheel, 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}
{"title":"Strict Log-Subadditivity for Overpartition Rank","authors":"Helen W. J. Zhang, 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)< p(a)p(b))</span> for <span>(a,b>1)</span> and <span>(a+b>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) > {overline{N}}(b, c, n))</span> for <span>(0le a<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}
{"title":"Dominance Regions for Rank Two Cluster Algebras","authors":"Dylan Rupel, 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}
{"title":"Berkovich–Uncu Type Partition Inequalities Concerning Impermissible Sets and Perfect Power Frequencies","authors":"Damanvir Singh Binner, Neha Gupta, 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}
{"title":"Identifying Young Diagrams Among Residue Multisets","authors":"Salim Rostam","doi":"10.1007/s00026-023-00641-7","DOIUrl":"10.1007/s00026-023-00641-7","url":null,"abstract":"<div><p>To any Young diagram we can associate the multiset of residues of all its nodes. This paper is concerned with the inverse problem: given a multiset of elements of <span>(mathbb {Z}/emathbb {Z})</span>, does it comes from a Young diagram? We give a full solution in level one and a partial answer in higher levels for Young multidiagrams, using Fayers’s notions of core block and weight of a multipartition. We apply the result in level one to study a shift operation on partitions.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00641-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44460921","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":"A Non-aligning Variant of Generalized Turán Problems","authors":"Dániel Gerbner","doi":"10.1007/s00026-023-00640-8","DOIUrl":"10.1007/s00026-023-00640-8","url":null,"abstract":"<div><p>In the so-called generalized Turán problems we study the largest number of copies of <i>H</i> in an <i>n</i>-vertex <i>F</i>-free graph <i>G</i>. Here we introduce a variant, where <i>F</i> is not forbidden, but we restrict how copies of <i>H</i> and <i>F</i> can be placed in <i>G</i>. More precisely, given an integer <i>n</i> and graphs <i>H</i> and <i>F</i>, what is the largest number of copies of <i>H</i> in an <i>n</i>-vertex graph such that the vertex set of that copy does not contain and is not contained in the vertex set of a copy of <i>F</i>? We solve this problem for some instances, give bounds in other instances, and we use our results to determine the generalized Turán number for some pairs of graphs.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-023-00640-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44545476","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":"Lattice Paths and Negatively Indexed Weight-Dependent Binomial Coefficients","authors":"Josef Küstner, Michael J. Schlosser, 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}
{"title":"Coloring Bipartite Graphs with Semi-small List Size","authors":"Daniel G. Zhu","doi":"10.1007/s00026-022-00633-z","DOIUrl":"10.1007/s00026-022-00633-z","url":null,"abstract":"<div><p>Recently, Alon, Cambie, and Kang introduced asymmetric list coloring of bipartite graphs, where the size of each vertex’s list depends on its part. For complete bipartite graphs, we fix the list sizes of one part and consider the resulting asymptotics, revealing an invariant quantity instrumental in determining choosability across most of the parameter space. By connecting this quantity to a simple question on independent sets of hypergraphs, we strengthen bounds when a part has list size 2. Finally, we state via our framework a conjecture on general bipartite graphs, unifying three conjectures of Alon–Cambie–Kang.</p></div>","PeriodicalId":50769,"journal":{"name":"Annals of Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00026-022-00633-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41929728","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}