{"title":"Positive semigroups and generalized Frobenius numbers over totally real number fields","authors":"L. Fukshansky, Yingqi Shi","doi":"10.2140/moscow.2020.9.29","DOIUrl":"https://doi.org/10.2140/moscow.2020.9.29","url":null,"abstract":"Frobenius problem and its many generalizations have been extensively studied in several areas of mathematics. We study semigroups of totally positive algebraic integers in totally real number fields, defining analogues of the Frobenius numbers in this context. We use a geometric framework recently introduced by Aliev, De Loera and Louveaux to produce upper bounds on these Frobenius numbers in terms of a certain height function. We discuss some properties of this function, relating it to absolute Weil height and obtaining a lower bound in the spirit of Lehmer's conjecture for algebraic vectors satisfying some special conditions. We also use a result of Borosh and Treybig to obtain bounds on the size of representations and number of elements of bounded height in such positive semigroups of totally real algebraic integers.","PeriodicalId":36590,"journal":{"name":"Moscow Journal of Combinatorics and Number Theory","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2140/moscow.2020.9.29","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43020807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Convexity Criterion for Unique Ergodicity of Interval Exchange Transformations","authors":"René Rühr","doi":"10.2140/MOSCOW.2020.9.51","DOIUrl":"https://doi.org/10.2140/MOSCOW.2020.9.51","url":null,"abstract":"A criterion for unique ergodicity for points of a curve in the space of interval exchange transformation is given.","PeriodicalId":36590,"journal":{"name":"Moscow Journal of Combinatorics and Number Theory","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2140/MOSCOW.2020.9.51","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68080655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Counting formulas for CM-types","authors":"Masanari Kida","doi":"10.2140/moscow.2019.8.343","DOIUrl":"https://doi.org/10.2140/moscow.2019.8.343","url":null,"abstract":"","PeriodicalId":36590,"journal":{"name":"Moscow Journal of Combinatorics and Number Theory","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2140/moscow.2019.8.343","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46930094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the domination number of a graph defined by containment","authors":"P. Frankl","doi":"10.2140/moscow.2019.8.379","DOIUrl":"https://doi.org/10.2140/moscow.2019.8.379","url":null,"abstract":"","PeriodicalId":36590,"journal":{"name":"Moscow Journal of Combinatorics and Number Theory","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2140/moscow.2019.8.379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41675960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Correction to the article Intersection theorems\u0000for (−1,0,1)-vectors and s-cross-intersecting families","authors":"P. Frankl, A. Kupavskii","doi":"10.2140/moscow.2019.8.385","DOIUrl":"https://doi.org/10.2140/moscow.2019.8.385","url":null,"abstract":"In this paper we study two directions of extending the classical ErdH os-Ko-Rado theorem which states that any family of $k$-element subsets of the set $[n] = {1,ldots,n}$ in which any two sets intersect, has cardinality at most ${n-1choose k-1}$. \u0000In the first part of the paper we study the families of ${0,pm 1}$-vectors. Denote by $mathcal L_k$ the family of all vectors $mathbf v$ from ${0,pm 1}^n$ such that $langlemathbf v,mathbf vrangle = k$. For any $k$ and $l$ and sufficiently large $n$ we determine the maximal size of the family $mathcal Vsubset mathcal L_k$ such that for any $mathbf v,mathbf win mathcal V$ we have $langle mathbf v,mathbf wranglege l$. We find some exact values of this function for all $n$ for small values of $k$. \u0000In the second part of the paper we study cross-intersecting pairs of families. We say that two families are $mathcal A, mathcal B$ are textit{$s$-cross-intersecting}, if for any $Ainmathcal A,Bin mathcal B$ we have $|Acap B|ge s$. We also say that a set family $mathcal A$ is textit{$t$-intersecting}, if for any $A_1,A_2in mathcal A$ we have $|A_1cap A_2|ge t$. For a pair of nonempty $s$-cross-intersecting $t$-intersecting families $mathcal A,mathcal B$ of $k$-sets, we determine the maximal value of $|mathcal A|+|mathcal B|$ for $n$ sufficiently large. \u0000If the nonempty families $mathcal A,mathcal B$ are $s$-cross-intersecting (and the $t$-intersecting condition is omitted), then we determine the maximum of $|mathcal A|+|mathcal B|$ for all $n$. This generalizes a result of Hilton and Milner, who determined the maximum of $|mathcal A|+|mathcal B|$ for nonempty $1$-cross-intersecting families.","PeriodicalId":36590,"journal":{"name":"Moscow Journal of Combinatorics and Number Theory","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2140/moscow.2019.8.385","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43572365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}