Semigroup ForumPub Date : 2024-04-05DOI: 10.1007/s00233-024-10424-y
Yevhen Zelenyuk
{"title":"Finite semigroups and periodic sums systems in $$beta mathbb {N}$$ and their Ramsey theoretic consequences","authors":"Yevhen Zelenyuk","doi":"10.1007/s00233-024-10424-y","DOIUrl":"https://doi.org/10.1007/s00233-024-10424-y","url":null,"abstract":"<p>Let <span>(m,nge 2)</span> and define <span>(nu :omega rightarrow {0,ldots ,m-1})</span> by <span>(nu (k)equiv kpmod {m})</span>. We construct some new finite semigroups in <span>(beta mathbb {N})</span>, in particular, a semigroup generated by <i>m</i> elements of order <i>n</i> with cardinality <span>(m^n+m^{n-1}+cdots +m)</span>. We also show that, for <span>(nge m)</span>, there is a sequence <span>(p_0,ldots ,p_{m-1})</span> in <span>(beta mathbb {N})</span> such that all sums <span>(sum _{j=i}^{i+k}p_{nu (j)})</span>, where <span>(iin {0,ldots ,m-1})</span> and <span>(kin {0,ldots ,n-1})</span>, are distinct and <span>(sum _{j=i}^{i+n}p_{nu (j)}=sum _{j=i}^{i+n-m}p_{nu (j)})</span> for each <i>i</i>. As consequences we derive some new Ramsey theoretic results. In particular, we show that, for <span>(nge m)</span>, there is a partition <span>({A_{i,k}:(i,k)in {0,ldots ,m-1}times {0,ldots ,n-1}})</span> of <span>(mathbb {N})</span> such that, whenever for each (<i>i</i>, <i>k</i>), <span>(mathscr {B}_{i,k})</span> is a finite partition of <span>(A_{i,k})</span>, there exist <span>(B_{i,k}in mathscr {B}_{i,k})</span> and a sequence <span>((x_j)_{j=0}^infty )</span> such that for every finite sequence <span>(j_0<ldots <j_s)</span> such that <span>(j_{t+1}equiv j_t+1pmod {m})</span> for each <span>(t<s)</span>, one has <span>(x_{j_0}+cdots +x_{j_s}in B_{i_0,k_0})</span>, where <span>(i_0=nu (j_0))</span> and <span>(k_0)</span> is <i>s</i> if <span>(sle n-1)</span> and <span>(n-m+nu (s-n))</span> otherwise.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"75 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140577923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Set-theoretical solutions of the pentagon equation on Clifford semigroups","authors":"Marzia Mazzotta, Vicent Pérez-Calabuig, Paola Stefanelli","doi":"10.1007/s00233-024-10421-1","DOIUrl":"https://doi.org/10.1007/s00233-024-10421-1","url":null,"abstract":"<p>Given a set-theoretical solution of the pentagon equation <span>(s:Stimes Srightarrow Stimes S)</span> on a set <i>S</i> and writing <span>(s(a, b)=(acdot b,, theta _a(b)))</span>, with <span>(cdot )</span> a binary operation on <i>S</i> and <span>(theta _a)</span> a map from <i>S</i> into itself, for every <span>(ain S)</span>, one naturally obtains that <span>(left( S,,cdot right) )</span> is a semigroup. In this paper, we focus on solutions defined in Clifford semigroups <span>(left( S,,cdot right) )</span> satisfying special properties on the set of all idempotents <span>({{,textrm{E},}}(S))</span>. Into the specific, we provide a complete description of <i>idempotent-invariant solutions</i>, namely, those solutions for which <span>(theta _a)</span> remains invariant in <span>({{,textrm{E},}}(S))</span>, for every <span>(ain S)</span>. Moreover, we construct a family of <i>idempotent-fixed solutions</i>, i.e., those solutions for which <span>(theta _a)</span> fixes every element in <span>({{,textrm{E},}}(S))</span> for every <span>(ain S)</span>, from solutions given on each maximal subgroup of <i>S</i>.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"49 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140311020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-03-27DOI: 10.1007/s00233-024-10422-0
Kritsada Sangkhanan, Jintana Sanwong
{"title":"The natural partial order on semigroups of transformations with restricted range that preserve an equivalence","authors":"Kritsada Sangkhanan, Jintana Sanwong","doi":"10.1007/s00233-024-10422-0","DOIUrl":"https://doi.org/10.1007/s00233-024-10422-0","url":null,"abstract":"<p>Let <i>Y</i> be a nonempty subset of <i>X</i> and <i>T</i>(<i>X</i>, <i>Y</i>) the set of all functions from <i>X</i> into <i>Y</i>. Then <i>T</i>(<i>X</i>, <i>Y</i>) with composition is a subsemigroup of the full transformation semigroup <i>T</i>(<i>X</i>). Let <i>E</i> be a nontrivial equivalence on <i>X</i>. Define a subsemigroup <span>(T_E(X,Y))</span> of <i>T</i>(<i>X</i>, <i>Y</i>) by </p><span>$$begin{aligned} T_E(X,Y)={alpha in T(X,Y):forall (x,y)in E, (xalpha ,yalpha )in E}. end{aligned}$$</span><p>We study <span>(T_E(X,Y))</span> with the natural partial order and determine when two elements are related under this order. We also give a characterization of compatibility on <span>(T_E(X,Y))</span> and then describe the maximal and minimal elements.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"58 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140310940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-03-22DOI: 10.1007/s00233-024-10419-9
Zayd Hajjej
{"title":"Exponential stability of extensible beams equation with Balakrishnan–Taylor, strong and localized nonlinear damping","authors":"Zayd Hajjej","doi":"10.1007/s00233-024-10419-9","DOIUrl":"https://doi.org/10.1007/s00233-024-10419-9","url":null,"abstract":"<p>We study a nonlinear Cauchy problem modeling the motion of an extensible beam </p><span>$$begin{aligned} vert y_tvert ^{r}y_{tt}{} & {} +gamma Delta ^2 y_{tt}+Delta ^2y-left( a+bvert vert nabla yvert vert ^2+c (nabla y, nabla y_t)right) Delta y{} & {} quad +Delta ^2 y_t+ d(x)h(y_t)+f(y)=0, end{aligned}$$</span><p>in a bounded domain of <span>(mathbb {R}^N)</span>, with clamped boundary conditions in either cases: when <span>(r=gamma =0)</span> or else when <i>r</i> and <span>(gamma )</span> are positive. We prove, in both cases, the existence of solutions and the exponential decay of energy.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"12 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140197258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-03-22DOI: 10.1007/s00233-024-10416-y
Meral Süer, Mehmet Yeşil
{"title":"Row-factorization matrices in Arf numerical semigroups and defining ideals","authors":"Meral Süer, Mehmet Yeşil","doi":"10.1007/s00233-024-10416-y","DOIUrl":"https://doi.org/10.1007/s00233-024-10416-y","url":null,"abstract":"<p>In this paper, we investigate the row-factorization matrices of Arf numerical semigroups, and we provide the full list of such matrices of certain Arf numerical semigroups. We use the information of row-factorization matrices to detect the generic nature and to find generators of the defining ideals.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"19 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140197256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-03-20DOI: 10.1007/s00233-024-10420-2
Yanan Wu, Miaomiao Ren, Xianzhong Zhao
{"title":"The additively idempotent semiring $$S_7^0$$ is nonfinitely based","authors":"Yanan Wu, Miaomiao Ren, Xianzhong Zhao","doi":"10.1007/s00233-024-10420-2","DOIUrl":"https://doi.org/10.1007/s00233-024-10420-2","url":null,"abstract":"<p>We show that the additively idempotent semiring <span>(S_7^0)</span> has no finite basis for its equational theory. This answers an open problem posed by Jackson et al. (J Algebra 611:211–245, 2022).</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"27 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140197254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-03-19DOI: 10.1007/s00233-024-10415-z
Christian Budde, Josef Kreulich
{"title":"On splittings and integration of almost periodic functions with and without geometry","authors":"Christian Budde, Josef Kreulich","doi":"10.1007/s00233-024-10415-z","DOIUrl":"https://doi.org/10.1007/s00233-024-10415-z","url":null,"abstract":"<p>Recently, the authors introduced the notion of weighted semigroups which apply to sun-dual semigroups and especially to the translation semigroup on the space of left continuous functions with values in dual spaces. In this article, we will show that it is sufficient that we either assume geometry on the Banach, or an abelian structure on the minimal subgroup to prove almost periodicity. This yields a different approach to the almost periodicity of semigroups and integrals, by extending Basit generalized Kadets result to general groups, to obtain almost periodicity.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"23 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140165511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-03-11DOI: 10.1007/s00233-024-10414-0
{"title":"Difference of Hilbert series of homogeneous monoid algebras and their normalizations","authors":"","doi":"10.1007/s00233-024-10414-0","DOIUrl":"https://doi.org/10.1007/s00233-024-10414-0","url":null,"abstract":"<h3>Abstract</h3> <p>Let <em>Q</em> be an affine monoid, <span> <span>(Bbbk [Q])</span> </span> the associated monoid <span> <span>(Bbbk )</span> </span>-algebra, and <span> <span>(Bbbk [overline{Q}])</span> </span> its normalization, where we let <span> <span>(Bbbk )</span> </span> be a field. We discuss a difference of the Hilbert series of <span> <span>(Bbbk [Q])</span> </span> and <span> <span>(Bbbk [overline{Q}])</span> </span> in the case where <span> <span>(Bbbk [Q])</span> </span> is homogeneous (i.e., standard graded). More precisely, we prove that if <span> <span>(Bbbk [Q])</span> </span> satisfies Serre’s condition <span> <span>((S_2))</span> </span>, then the degree of the <em>h</em>-polynomial of <span> <span>(Bbbk [Q])</span> </span> is always greater than or equal to that of <span> <span>(Bbbk [overline{Q}])</span> </span>. Moreover, we also show counterexamples of this statement if we drop the assumption <span> <span>((S_2))</span> </span>.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"71 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140115449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-03-06DOI: 10.1007/s00233-024-10417-x
Christian Budde, Marjeta Kramar Fijavž
{"title":"Well-posedness of non-autonomous transport equation on metric graphs","authors":"Christian Budde, Marjeta Kramar Fijavž","doi":"10.1007/s00233-024-10417-x","DOIUrl":"https://doi.org/10.1007/s00233-024-10417-x","url":null,"abstract":"<p>We consider transport processes on metric graphs with time-dependent velocities and show that, under continuity assumption of the velocity coefficients, the corresponding non-autonomous abstract Cauchy problem is well-posed by means of evolution families and evolution semigroups.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"121 1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140045409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semigroup ForumPub Date : 2024-02-23DOI: 10.1007/s00233-024-10413-1
{"title":"Combinatorial results for semigroups of orientation-preserving and order-decreasing transformations","authors":"","doi":"10.1007/s00233-024-10413-1","DOIUrl":"https://doi.org/10.1007/s00233-024-10413-1","url":null,"abstract":"<h3>Abstract</h3> <p>Let <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n})</span> </span> be the semigroup consisting of all orientation-preserving and order-decreasing full transformations on the finite chain <span> <span>(X_{n}={1<cdots <n})</span> </span>, and let <span> <span>(N({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n}))</span> </span> be the subsemigroup consisting of all nilpotent elements of <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n})</span> </span>. Moreover, for <span> <span>(1le rle n-1)</span> </span>, let <span> <span>$$begin{aligned} {{mathscr {O}}{mathscr {P}}{mathscr {D}}}(n,r) ={alpha in {{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n},:, |textrm{im},(alpha )|le r}, end{aligned}$$</span> </span>and let <span> <span>(N({{mathscr {O}}{mathscr {P}}{mathscr {D}}}(n,r)))</span> </span> be the subsemigroup consisting of all nilpotent elements of <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}(n,r))</span> </span>. In this paper, we compute the cardinalities of <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n})</span> </span>, <span> <span>(N({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n}))</span> </span>, <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}(n,r))</span> </span> and <span> <span>(N({{mathscr {O}}{mathscr {P}}{mathscr {D}}}(n,r)))</span> </span>, and find their ranks. Moreover, for each idempotent <span> <span>(xi )</span> </span> in <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n})</span> </span>, we show that <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n}(xi )={ alpha in {{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n} , alpha ^{m}=xi ,, text{ for } text{ some } ,, min {mathbb {N}} })</span> </span> is the maximal nilpotent subsemigroup of <span> <span>({{mathscr {O}}{mathscr {P}}{mathscr {D}}}_{n})</span> </span> with zero <span> <span>(xi )</span> </span>, and we find its cardinality and rank.</p>","PeriodicalId":49549,"journal":{"name":"Semigroup Forum","volume":"12 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139953366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}