{"title":"On malnormal peripheral subgroups of the fundamental group of a $3$-manifold","authors":"P. Harpe, Claude Weber","doi":"10.5802/CML.12","DOIUrl":"https://doi.org/10.5802/CML.12","url":null,"abstract":"Let K be a non-trivial knot in the 3-sphere, EK its exterior, GK = π1(EK) its group, and PK = π1(∂EK) ⊂ GK its peripheral subgroup. We show that PK is malnormal in GK , namely that gPKg ∩ PK = {e} for any g ∈ GK with g / ∈ PK , unless K is in one of the following three classes: torus knots, cable knots, and composite knots; these are exactly the classes for which there exist annuli in EK attached to TK which are not boundary parallel (Theorem 1 and Corollary 2). More generally, we characterise malnormal peripheral subgroups in the fundamental group of a compact orientable irreducible 3-manifold of which the boundary is a non-empty union of tori (Theorem 3). Proofs are written with non-expert readers in mind. Half of our paper (Appendices A to D) is a reminder of some three-manifold topology as it flourished before the Thurston revolution. In a companion paper [15], we collect general facts on malnormal subgroups and Frobenius groups, and we review a number of examples.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"2 1","pages":"41-64"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89914975","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":"Malnormal subgroups and Frobenius groups: basics and examples","authors":"P. Harpe, Claude Weber","doi":"10.5802/CML.13","DOIUrl":"https://doi.org/10.5802/CML.13","url":null,"abstract":"Malnormal subgroups occur in various contexts. We review a large number of examples, and compare the general situation to that of finite Frobenius groups of permutations. In a companion paper [18], we analyse when peripheral subgroups of knot groups and 3-manifold groups are malnormal.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"183 1","pages":"65-76"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74870386","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":"Ergodic Dilation of a Quantum Dynamical System","authors":"Carlo Pandiscia","doi":"10.5802/CML.14","DOIUrl":"https://doi.org/10.5802/CML.14","url":null,"abstract":". Using the Nagy dilation of linear contractions on Hilbert space and the Stinespring’s theorem for completely positive maps, we prove that any quantum dynamical system admits a dilation in the sense of Muhly and Solel which satisfies the same ergodic properties of the original quantum dynamical system.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"13 1","pages":"77-91"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81938802","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":"Espaces de Berkovich, polytopes, squelettes et théorie des modèles : erratum","authors":"A. Ducros","doi":"10.5802/CML.7","DOIUrl":"https://doi.org/10.5802/CML.7","url":null,"abstract":"L’accès aux articles de la revue « Confluentes Mathematici » (http://cml.cedram.org/), implique l’accord avec les conditions générales d’utilisation (http://cml.cedram.org/legal/). Toute reproduction en tout ou partie de cet article sous quelque forme que ce soit pour tout usage autre que l’utilisation á fin strictement personnelle du copiste est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"1014 1","pages":"43-44"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77174649","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":"Exponentiations over the quantum algebra $U_{q}(sl_2(mathbb{C}))$","authors":"Sonia L'Innocente, Françoise Point, C. Toffalori","doi":"10.5802/cml.8","DOIUrl":"https://doi.org/10.5802/cml.8","url":null,"abstract":"","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"8 1","pages":"45-69"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83415908","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":"Entre géométrie et théorie des substitutions : une étude de cas autour des vingt-sept droites d’une surface cubique","authors":"François Lê","doi":"10.5802/CML.2","DOIUrl":"https://doi.org/10.5802/CML.2","url":null,"abstract":"L’acces aux articles de la revue « Confluentes Mathematici » (http://cml.cedram.org/), implique l’accord avec les conditions generales d’utilisation (http://cml.cedram.org/legal/). Toute reproduction en tout ou partie de cet article sous quelque forme que ce soit pour tout usage autre que l’utilisation a fin strictement personnelle du copiste est constitutive d’une infraction penale. Toute copie ou impression de ce fichier doit contenir la presente mention de copyright.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"61 1","pages":"23-71"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77034179","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":"Finite Groups with some $s$-Permutably Embedded and Weakly $s$-Permutable Subgroups","authors":"Fenfang Xie, Jinjin Wang, Jiayi Xia, Guolei Zhong","doi":"10.5802/cml.4","DOIUrl":"https://doi.org/10.5802/cml.4","url":null,"abstract":"Let G be a finite group, p the smallest prime dividing the order of G and P a Sylow p-subgroup of G with the smallest generator number d. There is a set Md(P ) = {P1, P2, · · · , Pd} of maximal subgroups of P such that ⋂d i=1 Pi = Φ(P ). In the present paper, we investigate the structure of a finite group under the assumption that every member ofMd(P ) is either s-permutably embedded or weakly s-permutable in G to give criteria for a group to be p-supersolvable or p-nilpotent.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"103 1","pages":"93-100"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85382402","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":"INTERVAL EXCHANGE TRANSFORMATION EXTENSION OF A SUBSTITUTION DYNAMICAL SYSTEM","authors":"X. Bressaud, Y. Jullian","doi":"10.1142/S1793744212500053","DOIUrl":"https://doi.org/10.1142/S1793744212500053","url":null,"abstract":"Let α be a free group automorphism on FN with maximal index and Σα the associated attracting subshift. We prove that there exists an Interval Exchange Transformation on the circle whose coding factorizes onto Σα. In the case when there is an explicit construction of the ℝ-tree associated to α, we construct algorithmically such IET. We conclude by giving examples.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"57 1","pages":"1250005"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73263269","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":"Density of smooth maps for fractional Sobolev spaces $W^{s, p}$ into $ell$ simply connected manifolds when $s ge 1$","authors":"P. Bousquet, A. Ponce, Jean Van Schaftingen","doi":"10.5802/cml.5","DOIUrl":"https://doi.org/10.5802/cml.5","url":null,"abstract":"Given a compact manifold $N^n subset mathbb{R}^u$ and real numbers $s ge 1$ and $1 le p < infty$, we prove that the class $C^infty(overline{Q}^m; N^n)$ of smooth maps on the cube with values into $N^n$ is strongly dense in the fractional Sobolev space $W^{s, p}(Q^m; N^n)$ when $N^n$ is $lfloor sp floor$ simply connected. For $sp$ integer, we prove weak sequential density of $C^infty(overline{Q}^m; N^n)$ when $N^n$ is $sp - 1$ simply connected. The proofs are based on the existence of a retraction of $mathbb{^ u$ onto $N^n$ except for a small subset of $N^n$ and on a pointwise estimate of fractional derivatives of composition of maps in $W^{s, p} cap W^{1, sp}$.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"21 1","pages":"3-22"},"PeriodicalIF":0.0,"publicationDate":"2012-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87218992","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 STEINHAUS AND BERGMAN PROPERTIES FOR INFINITE PRODUCTS OF FINITE GROUPS","authors":"S. Thomas, J. Zapletal","doi":"10.1142/S1793744212500028","DOIUrl":"https://doi.org/10.1142/S1793744212500028","url":null,"abstract":"We study the relationship between the existence of nonprincipal ultrafilters over ω and the failure of the automatic continuity, Steinhaus and Bergman properties for infinite products of finite groups.","PeriodicalId":52130,"journal":{"name":"Confluentes Mathematici","volume":"20 4-6 1","pages":"1250002"},"PeriodicalIF":0.0,"publicationDate":"2012-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86566315","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}