{"title":"Construction of New Gyrogroups and the Structure of their Subgyrogroups","authors":"S. Mahdavi, A. Ashrafi, M. Salahshour","doi":"10.29252/AS.2020.1971","DOIUrl":"https://doi.org/10.29252/AS.2020.1971","url":null,"abstract":"Suppose that $G$ is a groupoid with binary operation $otimes$. The pair $(G,otimes)$ is said to be a gyrogroup if the operation $otimes$ has a left identity, each element $a in G$ has a left inverse and the gyroassociative law and the left loop property are satisfied in $G$. In this paper, a method for constructing new gyrogroups from old ones is presented and the structure of subgyrogroups of these gyrogroups are also given. As a consequence of this work, five $2-$gyrogroups of order $2^n$, $ngeq 3$, are presented. Some open questions are also proposed.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"82 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78660450","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":"GVZ-groups, Flat groups, and CM-Groups","authors":"Shawn T. Burkett, M. Lewis","doi":"10.5802/CRMATH.185","DOIUrl":"https://doi.org/10.5802/CRMATH.185","url":null,"abstract":"We show that a group is a GVZ-group if and only if it is a flat group. We show that the nilpotence class of a GVZ-group is bounded by the number of distinct degrees of irreducible characters. We also show that certain CM-groups can be characterized as GVZ-groups whose irreducible character values lie in the prime field.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83920269","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":"Embedding theorems for solvable groups","authors":"V. Roman’kov","doi":"10.1090/PROC/15562","DOIUrl":"https://doi.org/10.1090/PROC/15562","url":null,"abstract":"In this paper, we prove a series of results on group embeddings in groups with a small number of generators. We show that each finitely generated group $G$ lying in a variety ${mathcal M}$ can be embedded in a $4$-generated group $H in {mathcal M}{mathcal A}$ (${mathcal A}$ means the variety of abelian groups). If $G$ is a finite group, then $H$ can also be found as a finite group. It follows, that any finitely generated (finite) solvable group $G$ of the derived length $l$ can be embedded in a $4$-generated (finite) solvable group $H$ of length $l+1$. Thus, we answer the question of V. H. Mikaelian and this http URL. Olshanskii. It is also shown that any countable group $Gin {mathcal M}$, such that the abelianization $G_{ab}$ is a free abelian group, is embeddable in a $2$-generated group $Hin {mathcal M}{mathcal A}$.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75479948","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 coverings of Hantzsche-Wendt manifold","authors":"G. Chelnokov, A. Mednykh","doi":"10.2748/tmj.20210308","DOIUrl":"https://doi.org/10.2748/tmj.20210308","url":null,"abstract":"There are only 10 Euclidean forms, that is flat closed three dimensional manifolds: six are orientable $mathcal{G}_1,dots,mathcal{G}_6$ and four are non-orientable $mathcal{B}_1,dots,mathcal{B}_4$. In the present paper we investigate the manifold $mathcal{G}_6$, also known as Hantzsche-Wendt manifold; this is the unique Euclidean $3$-form with finite first homology group $H_1(mathcal{G}_6) = mathbb{Z}^2_4$. \u0000The aim of this paper is to describe all types of $n$-fold coverings over $mathcal{G}_{6}$ and calculate the numbers of non-equivalent coverings of each type. We classify subgroups in the fundamental group $pi_1(mathcal{G}_{6})$ up to isomorphism. Given index $n$, we calculate the numbers of subgroups and the numbers of conjugacy classes of subgroups for each isomorphism type and provide the Dirichlet generating series for the above sequences.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74755710","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":"An algorithm for finding minimal generating sets of finite groups.","authors":"Tanakorn Udomworarat, T. Suksumran","doi":"10.29252/AS.2021.2029","DOIUrl":"https://doi.org/10.29252/AS.2021.2029","url":null,"abstract":"In this article, we study connections between components of the Cayley graph $mathrm{Cay}(G,A)$, where $A$ is an arbitrary subset of a group $G$, and cosets of the subgroup of $G$ generated by $A$. In particular, we show how to construct generating sets of $G$ if $mathrm{Cay}(G,A)$ has finitely many components. Furthermore, we provide an algorithm for finding minimal generating sets of finite groups using their Cayley graphs.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85072077","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":"CAT(0) cube complexes with flat hyperplanes","authors":"A. Genevois","doi":"10.1090/PROC/15490","DOIUrl":"https://doi.org/10.1090/PROC/15490","url":null,"abstract":"In this short note, we show that a group acting geometrically on a CAT(0) cube complex with virtually abelian hyperplane-stabilisers must decompose virtually as a free product of free abelian groups and surface groups.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91380601","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 profinite rigidity of surface groups and surface words","authors":"H. Wilton","doi":"10.5802/CRMATH.121","DOIUrl":"https://doi.org/10.5802/CRMATH.121","url":null,"abstract":"Surface groups are determined among limit groups by their profinite completions. As a corollary, the set of surface words in a free group is closed in the profinite topology.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"67 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76162234","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":"Schur's exponent conjecture -- counterexamples of exponent 5 and exponent 9.","authors":"M. Vaughan-Lee","doi":"10.22108/IJGT.2020.123980.1638","DOIUrl":"https://doi.org/10.22108/IJGT.2020.123980.1638","url":null,"abstract":"There is a long-standing conjecture attributed to I Schur that if $G$ is a finite group with Schur multiplier $M(G)$ then the exponent of $M(G)$ divides the exponent of $G$. It is easy to see that this conjecture holds for exponent 2 and exponent 3, but it has been known since 1974 that the conjecture fails for exponent 4. In this note I give an example of a group $G$ with exponent 5 with Schur multiplier $M(G)$ of exponent 25, and an example of a group $A$ of exponent 9 with Schur multiplier $M(A)$ of exponent 27.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72942623","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":"Graph automaton groups","authors":"Matteo Cavaleri, D. D’Angeli, A. Donno, E. Rodaro","doi":"10.32037/agta-2021-005","DOIUrl":"https://doi.org/10.32037/agta-2021-005","url":null,"abstract":"In this paper we define a way to get a bounded invertible automaton starting from a finite graph. It turns out that the corresponding automaton group is regular weakly branch over its commutator subgroup, contains a free semigroup on two elements and is amenable of exponential growth. We also highlight a connection between our construction and the right-angled Artin groups. We then study the Schreier graphs associated with the self-similar action of these automaton groups on the regular rooted tree. We explicitly determine their diameter and their automorphism group in the case where the initial graph is a path. Moreover, we show that the case of cycles gives rise to Schreier graphs whose automorphism group is isomorphic to the dihedral group. It is remarkable that our construction recovers some classical examples of automaton groups like the Adding machine and the Tangled odometer.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88010036","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":"McKay graphs for alternating and classical groups","authors":"M. Liebeck, A. Shalev, P. Tiep","doi":"10.1090/TRAN/8395","DOIUrl":"https://doi.org/10.1090/TRAN/8395","url":null,"abstract":"Let $G$ be a finite group, and $alpha$ a nontrivial character of $G$. The McKay graph $mathcal{M}(G,alpha)$ has the irreducible characters of $G$ as vertices, with an edge from $chi_1$ to $chi_2$ if $chi_2$ is a constituent of $alphachi_1$. We study the diameters of McKay graphs for finite simple groups $G$. For alternating groups, we prove a conjecture made in [LST]: there is an absolute constant $C$ such that $hbox{diam},{mathcal M}(G,alpha) le Cfrac{log |mathsf{A}_n|}{log alpha(1)}$ for all nontrivial irreducible characters $alpha$ of $mathsf{A}_n$. Also for classsical groups of symplectic or orthogonal type of rank $r$, we establish a linear upper bound $Cr$ on the diameters of all nontrivial McKay graphs.","PeriodicalId":8427,"journal":{"name":"arXiv: Group Theory","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91326769","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}
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