首页 > 最新文献

Topology and its Applications最新文献

英文 中文
On local compactness, pseudocompactness, and homogeneity 关于局部紧性、伪紧性和齐性
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-10-28 DOI: 10.1016/j.topol.2025.109653
Nathan Carlson
We give a new bound for the cardinality of a Tychonoff homogeneous space using cozero sets. This leads to improved cardinal inequalities for compact homogeneous spaces that generalize to the locally compact setting. In this connection it is also shown that w(X)nw(X)pct(X) for any Hausdorff space X, where pct(X) is the point-wise compactness type of X. This extends Arhangel′skiĭ's result that w(X)=nw(X) when X is compact Hausdorff. In addition pseudocompactness is investigated in connection with homogeneity. Among other results, we show that if X is a ccc locally compact noncompact space such that the one-point compactification of X is homogeneous and has character c, then X is pseudocompact. It follows that if X is either [0,1]c or 2c and pX then X{p} is pseudocompact.
利用余零集给出了Tychonoff齐次空间的基性的一个新界。这导致改进的基数不等式的紧齐次空间,推广到局部紧设置。由此还证明了对于任意Hausdorff空间X, w(X)≤nw(X)pct(X),其中pct(X)是X的点向紧性类型。这推广了Arhangel’ski’的结论,即当X是紧Hausdorff时w(X)=nw(X)。此外,还研究了赝紧性与均匀性的关系。在其他结果中,我们证明了如果X是ccc局部紧非紧空间,使得X的一点紧化齐次且具有特征c,则X是伪紧的。因此,如果X是[0,1]c或2c,且p∈X,则X{p}是伪紧的。
{"title":"On local compactness, pseudocompactness, and homogeneity","authors":"Nathan Carlson","doi":"10.1016/j.topol.2025.109653","DOIUrl":"10.1016/j.topol.2025.109653","url":null,"abstract":"<div><div>We give a new bound for the cardinality of a Tychonoff homogeneous space using cozero sets. This leads to improved cardinal inequalities for compact homogeneous spaces that generalize to the locally compact setting. In this connection it is also shown that <span><math><mi>w</mi><mo>(</mo><mi>X</mi><mo>)</mo><mo>≤</mo><mi>n</mi><mi>w</mi><msup><mrow><mo>(</mo><mi>X</mi><mo>)</mo></mrow><mrow><mi>p</mi><mi>c</mi><mi>t</mi><mo>(</mo><mi>X</mi><mo>)</mo></mrow></msup></math></span> for any Hausdorff space <em>X</em>, where <span><math><mi>p</mi><mi>c</mi><mi>t</mi><mo>(</mo><mi>X</mi><mo>)</mo></math></span> is the point-wise compactness type of <em>X</em>. This extends Arhangel′skiĭ's result that <span><math><mi>w</mi><mo>(</mo><mi>X</mi><mo>)</mo><mo>=</mo><mi>n</mi><mi>w</mi><mo>(</mo><mi>X</mi><mo>)</mo></math></span> when <em>X</em> is compact Hausdorff. In addition pseudocompactness is investigated in connection with homogeneity. Among other results, we show that if <em>X</em> is a ccc locally compact noncompact space such that the one-point compactification of <em>X</em> is homogeneous and has character <span><math><mi>c</mi></math></span>, then <em>X</em> is pseudocompact. It follows that if <em>X</em> is either <span><math><msup><mrow><mo>[</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>]</mo></mrow><mrow><mi>c</mi></mrow></msup></math></span> or <span><math><msup><mrow><mn>2</mn></mrow><mrow><mi>c</mi></mrow></msup></math></span> and <span><math><mi>p</mi><mo>∈</mo><mi>X</mi></math></span> then <span><math><mi>X</mi><mo>﹨</mo><mo>{</mo><mi>p</mi><mo>}</mo></math></span> is pseudocompact.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109653"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418097","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}
引用次数: 0
Indecomposability of group actions 群体行为的不可分解性
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-10-30 DOI: 10.1016/j.topol.2025.109652
Ashwani K B, Ali Akbar K
A chaotic group action is a nonminimal, topologically transitive continuous group action with dense periodic points. In this paper, we discuss indecomposability for a continuous group action and prove that indecomposability is an equivalent definition of topological transitivity. Moreover, we prove that any infinite compact subset of the real line having a chaotic group action is homeomorphic to the middle third Cantor set.
混沌群作用是具有密集周期点的非极小、拓扑可传递的连续群作用。本文讨论了连续群作用的不可分解性,并证明了不可分解性是拓扑传递性的等价定义。此外,我们证明了具有混沌群作用的实线的无限紧子集与中三分之一康托集是同纯的。
{"title":"Indecomposability of group actions","authors":"Ashwani K B,&nbsp;Ali Akbar K","doi":"10.1016/j.topol.2025.109652","DOIUrl":"10.1016/j.topol.2025.109652","url":null,"abstract":"<div><div>A chaotic group action is a nonminimal, topologically transitive continuous group action with dense periodic points. In this paper, we discuss indecomposability for a continuous group action and prove that indecomposability is an equivalent definition of topological transitivity. Moreover, we prove that any infinite compact subset of the real line having a chaotic group action is homeomorphic to the middle third Cantor set.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109652"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466892","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}
引用次数: 0
Constructions of and bounds on the toric mosaic number 复向镶嵌数的构造及界
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-10-31 DOI: 10.1016/j.topol.2025.109657
Kendall Heiney , Margaret Kipe , Samantha Pezzimenti , Kaelyn Pontes , Lực Ta
Knot mosaics were introduced by Kauffman and Lomonaco in the context of quantum knots, but have since been studied for their own right. A classical knot mosaic is formed on a square grid. In this work, we identify opposite edges of the square to form mosaics on the surface of a torus. We provide two algorithms for efficiently constructing toric mosaics of torus knots, providing upper bounds for the toric mosaic number. Using these results and a computer search, we provide a census of known toric mosaic numbers.
结镶嵌是由Kauffman和Lomonaco在量子结的背景下引入的,但后来被研究了自己的权利。一个经典的花结镶嵌在方形网格上。在这个作品中,我们识别出正方形的相对边缘,在一个环面的表面上形成马赛克。我们提供了两种有效构造环面结点的环面镶嵌的算法,并给出了环面镶嵌数的上界。利用这些结果和计算机搜索,我们提供了已知环面马赛克数的普查。
{"title":"Constructions of and bounds on the toric mosaic number","authors":"Kendall Heiney ,&nbsp;Margaret Kipe ,&nbsp;Samantha Pezzimenti ,&nbsp;Kaelyn Pontes ,&nbsp;Lực Ta","doi":"10.1016/j.topol.2025.109657","DOIUrl":"10.1016/j.topol.2025.109657","url":null,"abstract":"<div><div>Knot mosaics were introduced by Kauffman and Lomonaco in the context of quantum knots, but have since been studied for their own right. A classical knot mosaic is formed on a square grid. In this work, we identify opposite edges of the square to form mosaics on the surface of a torus. We provide two algorithms for efficiently constructing toric mosaics of torus knots, providing upper bounds for the toric mosaic number. Using these results and a computer search, we provide a census of known toric mosaic numbers.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109657"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466891","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}
引用次数: 0
On fundamental groups of spaces of framed embeddings of a circle in a 4-manifold 关于4流形中圆的框架嵌入空间的基本群
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-11-11 DOI: 10.1016/j.topol.2025.109658
Danica Kosanović
Motivated by recent results on diffeomorphisms of 4-manifolds, this paper investigates fundamental groups of spaces of embeddings of S1×D3 in 4-manifolds. The majority of work goes into the case of framed immersed circles.
在最近关于4流形的微分同态的研究结果的启发下,本文研究了4流形中S1×D3嵌入空间的基本群。大部分工作都是在框架浸入式圆的情况下进行的。
{"title":"On fundamental groups of spaces of framed embeddings of a circle in a 4-manifold","authors":"Danica Kosanović","doi":"10.1016/j.topol.2025.109658","DOIUrl":"10.1016/j.topol.2025.109658","url":null,"abstract":"<div><div>Motivated by recent results on diffeomorphisms of 4-manifolds, this paper investigates fundamental groups of spaces of embeddings of <span><math><msup><mrow><mi>S</mi></mrow><mrow><mn>1</mn></mrow></msup><mo>×</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>3</mn></mrow></msup></math></span> in 4-manifolds. The majority of work goes into the case of framed immersed circles.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109658"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520225","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}
引用次数: 0
Topologies and fixpoints on weak partial metric spaces 弱偏度量空间上的拓扑与不动点
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-10-02 DOI: 10.1016/j.topol.2025.109601
Mengqiao Huang , Xiaodong Jia , Qingguo Li
For a weak partial metric space (X,p), there is a canonical metric mp on X, defined as mp(x,y)=max{p(x,y)p(x,x),p(x,y)p(y,y)} for all x,yX. We prove that the partial metric topology and the Scott topology on (X,p) coincide if and only if the metric topology on (X,mp) and the Lawson topology on (X,p) agree, provided that the weak partial metric space (X,p) is a domain in its specialization order and its associated metric space (X,mp) is compact. We also discussed fixpoints of self maps defined on weak partial metric spaces.
对于一个弱偏度量空间(X,p),在X上存在一个正则度量mp,定义为mp(X, y)=max (p(X, y) - p(X, X),p(X, y) - p(y,y)},对于所有X, y∈X。我们证明了当且仅当(X,mp)上的度量拓扑与(X,p)上的Lawson拓扑一致时,(X,p)上的偏度量拓扑与(X,p)上的Scott拓扑重合,前提是弱偏度量空间(X,p)是专一阶的定域,且其关联的度量空间(X,mp)是紧的。讨论了弱偏度量空间上自映射的不动点。
{"title":"Topologies and fixpoints on weak partial metric spaces","authors":"Mengqiao Huang ,&nbsp;Xiaodong Jia ,&nbsp;Qingguo Li","doi":"10.1016/j.topol.2025.109601","DOIUrl":"10.1016/j.topol.2025.109601","url":null,"abstract":"<div><div>For a weak partial metric space <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>p</mi><mo>)</mo></math></span>, there is a canonical metric <span><math><msub><mrow><mi>m</mi></mrow><mrow><mi>p</mi></mrow></msub></math></span> on <em>X</em>, defined as <span><math><msub><mrow><mi>m</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo><mo>=</mo><mi>max</mi><mo>⁡</mo><mo>{</mo><mi>p</mi><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo><mo>−</mo><mi>p</mi><mo>(</mo><mi>x</mi><mo>,</mo><mi>x</mi><mo>)</mo><mo>,</mo><mi>p</mi><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo><mo>−</mo><mi>p</mi><mo>(</mo><mi>y</mi><mo>,</mo><mi>y</mi><mo>)</mo><mo>}</mo></math></span> for all <span><math><mi>x</mi><mo>,</mo><mi>y</mi><mo>∈</mo><mi>X</mi></math></span>. We prove that the partial metric topology and the Scott topology on <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>p</mi><mo>)</mo></math></span> coincide if and only if the metric topology on <span><math><mo>(</mo><mi>X</mi><mo>,</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>)</mo></math></span> and the Lawson topology on <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>p</mi><mo>)</mo></math></span> agree, provided that the weak partial metric space <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>p</mi><mo>)</mo></math></span> is a domain in its specialization order and its associated metric space <span><math><mo>(</mo><mi>X</mi><mo>,</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>)</mo></math></span> is compact. We also discussed fixpoints of self maps defined on weak partial metric spaces.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109601"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269836","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}
引用次数: 0
Rational cohomology and Cartan matrix 有理上同调与卡坦矩阵
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-09-30 DOI: 10.1016/j.topol.2025.109603
Chi-Heng Zhang , Nan Gao , Zi-Cheng Cheng
Gabrel-Krause dimension of the rational cohomology H(BTm;Q) is described for the m-torus Tm. Inspired by the diagonalizability of admissible map between H(BTm,Q), the relationship of minimal realization among symmetrizable generalised Cartan matrices is shown.
描述了m-环面Tm的有理上同调H _ (BTm;Q)的Gabrel-Krause维数。利用H ~ (BTm,Q)间可容许映射的对角性,给出了可对称广义Cartan矩阵间最小实现的关系。
{"title":"Rational cohomology and Cartan matrix","authors":"Chi-Heng Zhang ,&nbsp;Nan Gao ,&nbsp;Zi-Cheng Cheng","doi":"10.1016/j.topol.2025.109603","DOIUrl":"10.1016/j.topol.2025.109603","url":null,"abstract":"<div><div>Gabrel-Krause dimension of the rational cohomology <span><math><msup><mrow><mi>H</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>(</mo><mi>B</mi><msup><mrow><mi>T</mi></mrow><mrow><mi>m</mi></mrow></msup><mo>;</mo><mi>Q</mi><mo>)</mo></math></span> is described for the <em>m</em>-torus <span><math><msup><mrow><mi>T</mi></mrow><mrow><mi>m</mi></mrow></msup></math></span>. Inspired by the diagonalizability of admissible map between <span><math><msup><mrow><mi>H</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>(</mo><mi>B</mi><msup><mrow><mi>T</mi></mrow><mrow><mi>m</mi></mrow></msup><mo>,</mo><mi>Q</mi><mo>)</mo></math></span>, the relationship of minimal realization among symmetrizable generalised Cartan matrices is shown.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109603"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269841","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}
引用次数: 0
Preservation and reflection of separation axioms by essentially Kolmogorov and Kolmogorov relations 柯尔莫哥洛夫和柯尔莫哥洛夫关系对分离公理的保存和反映
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-09-03 DOI: 10.1016/j.topol.2025.109574
Jeffrey T. Denniston , Stephen E. Rodabaugh , Jamal K. Tartir
This paper focuses on the Kolmogorov functor K:TopTop0 and associated ideas. There are two main objectives: first, catalogue and prove those topological invariants which K both preserves and reflects, called “Hong” invariants; and second, give a step-by-step axiomatic foundation for K to analyze its remarkable success in having so many Hong invariants. Pursuing the second objective leads to “essentially Kolmogorov” (EK) relations, the family of which on a ground set forms a complete lattice ordered by inclusion; the diagonal relation Δ is the universal lower bound and the Kolmogorov relation K is the universal upper bound—typically there are many EK relations strictly between Δ and K. Though EK relations are significant weakenings of K, they enjoy the same success w.r.t. Hong invariants. Counterexamples clarify relationships between similar notions.
本文主要研究Kolmogorov函子K:Top→Top0及其相关思想。主要有两个目标:第一,列出并证明K既保留又反映的拓扑不变量,称为“Hong”不变量;其次,为K给出一个逐步的公理基础,以分析它在拥有如此多的Hong不变量方面取得的显著成功。追求第二个目标会导致“本质Kolmogorov”(EK)关系,这种关系族在一个基集上形成一个由包含有序的完整晶格;对角线关系Δ是普遍下界,Kolmogorov关系K是普遍上界——通常在Δ和K之间严格存在许多EK关系,尽管EK关系是K的显著弱化,但它们在r.t Hong不变量中同样成功。反例阐明相似概念之间的关系。
{"title":"Preservation and reflection of separation axioms by essentially Kolmogorov and Kolmogorov relations","authors":"Jeffrey T. Denniston ,&nbsp;Stephen E. Rodabaugh ,&nbsp;Jamal K. Tartir","doi":"10.1016/j.topol.2025.109574","DOIUrl":"10.1016/j.topol.2025.109574","url":null,"abstract":"<div><div>This paper focuses on the Kolmogorov functor <span><math><mi>K</mi><mo>:</mo><mrow><mi>Top</mi></mrow><mo>→</mo><msub><mrow><mi>Top</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> and associated ideas. There are two main objectives: first, catalogue and prove those topological invariants which <em>K</em> both preserves and reflects, called “Hong” invariants; and second, give a step-by-step axiomatic foundation for <em>K</em> to analyze its remarkable success in having so many Hong invariants. Pursuing the second objective leads to “essentially Kolmogorov” (EK) relations, the family of which on a ground set forms a complete lattice ordered by inclusion; the diagonal relation Δ is the universal lower bound and the Kolmogorov relation <em>K</em> is the universal upper bound—typically there are many EK relations strictly between Δ and <em>K</em>. Though EK relations are significant weakenings of <em>K</em>, they enjoy the same success w.r.t. Hong invariants. Counterexamples clarify relationships between similar notions.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109574"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145222986","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}
引用次数: 0
Some notes on topological rings and their groups of units 拓扑环及其单位群的若干注释
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-09-25 DOI: 10.1016/j.topol.2025.109600
Abolfazl Tarizadeh
If R is a topological ring then R, the group of units of R, with the subspace topology is not necessarily a topological group. This leads us to the following natural definition: By absolute topological ring we mean a topological ring such that its group of units with the subspace topology is a topological group. We prove that every commutative ring with the I-adic topology is an absolute topological ring (where I is an ideal of the ring).
Next, we prove that if I is an ideal of a ring R then for the I-adic topology over R we have π0(R)=R/(n1In)=t(R) where π0(R) is the space of connected components of R and t(R) is the space of irreducible closed subsets of R.
We also show with an example that the identity component of a topological group is not necessarily a characteristic subgroup.
Finally, we observed that the main result of Koh [3] as well as its corrected form [5, Chap II, §12, Theorem 12.1] is not true, and then we corrected this result in the right way.
如果R是一个拓扑环,那么R的单位群R,具有子空间拓扑不一定是一个拓扑群。这就引出了以下的自然定义:所谓绝对拓扑环,我们指的是这样一个拓扑环:它的具有子空间拓扑的单元群是一个拓扑群。证明了每一个具有I进进拓扑的交换环都是一个绝对拓扑环(其中I是环的理想)。接下来,我们证明如果I是环R的理想那么对于R上的I进进拓扑我们有π0(R)=R/(n或1In)=t(R)其中π0(R)是R的连通分量的空间t(R)是R的不可约闭子集的空间我们还用一个例子证明拓扑群的单位分量不一定是特征子群。最后,我们注意到Koh[3]的主要结果及其修正形式[5,第2章§12,定理12.1]是不正确的,然后我们以正确的方式修正了这个结果。
{"title":"Some notes on topological rings and their groups of units","authors":"Abolfazl Tarizadeh","doi":"10.1016/j.topol.2025.109600","DOIUrl":"10.1016/j.topol.2025.109600","url":null,"abstract":"<div><div>If <em>R</em> is a topological ring then <span><math><msup><mrow><mi>R</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span>, the group of units of <em>R</em>, with the subspace topology is not necessarily a topological group. This leads us to the following natural definition: By absolute topological ring we mean a topological ring such that its group of units with the subspace topology is a topological group. We prove that every commutative ring with the <em>I</em>-adic topology is an absolute topological ring (where <em>I</em> is an ideal of the ring).</div><div>Next, we prove that if <em>I</em> is an ideal of a ring <em>R</em> then for the <em>I</em>-adic topology over <em>R</em> we have <span><math><msub><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>(</mo><mi>R</mi><mo>)</mo><mo>=</mo><mi>R</mi><mo>/</mo><mo>(</mo><munder><mo>⋂</mo><mrow><mi>n</mi><mo>⩾</mo><mn>1</mn></mrow></munder><msup><mrow><mi>I</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>)</mo><mo>=</mo><mi>t</mi><mo>(</mo><mi>R</mi><mo>)</mo></math></span> where <span><math><msub><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>(</mo><mi>R</mi><mo>)</mo></math></span> is the space of connected components of <em>R</em> and <span><math><mi>t</mi><mo>(</mo><mi>R</mi><mo>)</mo></math></span> is the space of irreducible closed subsets of <em>R</em>.</div><div>We also show with an example that the identity component of a topological group is not necessarily a characteristic subgroup.</div><div>Finally, we observed that the main result of Koh <span><span>[3]</span></span> as well as its corrected form <span><span>[5, Chap II, §12, Theorem 12.1]</span></span> is not true, and then we corrected this result in the right way.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109600"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145183877","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}
引用次数: 0
Corrigendum to “Compact-star networks and the images of metric spaces under C-mappings” [Topol. Appl. 271 (2020) 107049] “紧凑型星形网络和c -映射下度量空间的图象”的勘误表。苹果。271 (2020)107049]
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-11-26 DOI: 10.1016/j.topol.2025.109666
Shou Lin , Ying Ge , Xiangeng Zhou
This note provides a corrigendum to the proof of Theorem 4.5 in Topol. Appl. 271 (2020) 107049.
本注释提供了对Topol中定理4.5的证明的更正。应用程序271(2020)107049。
{"title":"Corrigendum to “Compact-star networks and the images of metric spaces under C-mappings” [Topol. Appl. 271 (2020) 107049]","authors":"Shou Lin ,&nbsp;Ying Ge ,&nbsp;Xiangeng Zhou","doi":"10.1016/j.topol.2025.109666","DOIUrl":"10.1016/j.topol.2025.109666","url":null,"abstract":"<div><div>This note provides a corrigendum to the proof of Theorem 4.5 in Topol. Appl. 271 (2020) 107049.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109666"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617797","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}
引用次数: 0
A discrete topological complexity of discrete motion planning 离散运动规划的离散拓扑复杂性
IF 0.5 4区 数学 Q3 MATHEMATICS Pub Date : 2026-01-01 Epub Date: 2025-10-10 DOI: 10.1016/j.topol.2025.109634
Hadi Hassanzada, Hamid Torabi, Hanieh Mirebrahimi, Ameneh Babaee
In this paper, we present a framework for discrete motion planning tailored for robots that operate in a discrete manner. Furthermore, we extend the concept of r-discrete homotopy as discrete (s,r)-homotopy. Utilizing this framework, we investigate the notion of discrete topological complexity, which is defined as the least number of motion planning algorithms necessary for discrete movement. We establish several properties related to discrete topological complexity; for example, we demonstrate that discrete motion planning within a metric space X is feasible if and only if X is a discrete contractible space. Additionally, we show that the discrete topological complexity is solely determined by the strictly discrete homotopy type of the spaces involved.
在本文中,我们提出了一个为以离散方式操作的机器人量身定制的离散运动规划框架。进一步,我们将r-离散同伦的概念推广为离散(s,r)-同伦。利用这个框架,我们研究了离散拓扑复杂性的概念,它被定义为离散运动所需的最少数量的运动规划算法。我们建立了与离散拓扑复杂性相关的几个性质;例如,我们证明了度量空间X内的离散运动规划当且仅当X是一个离散可收缩空间时是可行的。此外,我们还证明了离散拓扑复杂度完全取决于所涉及空间的严格离散同伦类型。
{"title":"A discrete topological complexity of discrete motion planning","authors":"Hadi Hassanzada,&nbsp;Hamid Torabi,&nbsp;Hanieh Mirebrahimi,&nbsp;Ameneh Babaee","doi":"10.1016/j.topol.2025.109634","DOIUrl":"10.1016/j.topol.2025.109634","url":null,"abstract":"<div><div>In this paper, we present a framework for discrete motion planning tailored for robots that operate in a discrete manner. Furthermore, we extend the concept of <em>r</em>-discrete homotopy as discrete <span><math><mo>(</mo><mi>s</mi><mo>,</mo><mi>r</mi><mo>)</mo></math></span>-homotopy. Utilizing this framework, we investigate the notion of discrete topological complexity, which is defined as the least number of motion planning algorithms necessary for discrete movement. We establish several properties related to discrete topological complexity; for example, we demonstrate that discrete motion planning within a metric space <em>X</em> is feasible if and only if <em>X</em> is a discrete contractible space. Additionally, we show that the discrete topological complexity is solely determined by the strictly discrete homotopy type of the spaces involved.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"377 ","pages":"Article 109634"},"PeriodicalIF":0.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269844","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}
引用次数: 0
期刊
Topology and its Applications
全部 Acc. Chem. Res. ACS Applied Bio Materials ACS Appl. Electron. Mater. ACS Appl. Energy Mater. ACS Appl. Mater. Interfaces ACS Appl. Nano Mater. ACS Appl. Polym. Mater. ACS BIOMATER-SCI ENG ACS Catal. ACS Cent. Sci. ACS Chem. Biol. ACS Chemical Health & Safety ACS Chem. Neurosci. ACS Comb. Sci. ACS Earth Space Chem. ACS Energy Lett. ACS Infect. Dis. ACS Macro Lett. ACS Mater. Lett. ACS Med. Chem. Lett. ACS Nano ACS Omega ACS Photonics ACS Sens. ACS Sustainable Chem. Eng. ACS Synth. Biol. Anal. Chem. BIOCHEMISTRY-US Bioconjugate Chem. BIOMACROMOLECULES Chem. Res. Toxicol. Chem. Rev. Chem. Mater. CRYST GROWTH DES ENERG FUEL Environ. Sci. Technol. Environ. Sci. Technol. Lett. Eur. J. Inorg. Chem. IND ENG CHEM RES Inorg. Chem. J. Agric. Food. Chem. J. Chem. Eng. Data J. Chem. Educ. J. Chem. Inf. Model. J. Chem. Theory Comput. J. Med. Chem. J. Nat. Prod. J PROTEOME RES J. Am. Chem. Soc. LANGMUIR MACROMOLECULES Mol. Pharmaceutics Nano Lett. Org. Lett. ORG PROCESS RES DEV ORGANOMETALLICS J. Org. Chem. J. Phys. Chem. J. Phys. Chem. A J. Phys. Chem. B J. Phys. Chem. C J. Phys. Chem. Lett. Analyst Anal. Methods Biomater. Sci. Catal. Sci. Technol. Chem. Commun. Chem. Soc. Rev. CHEM EDUC RES PRACT CRYSTENGCOMM Dalton Trans. Energy Environ. Sci. ENVIRON SCI-NANO ENVIRON SCI-PROC IMP ENVIRON SCI-WAT RES Faraday Discuss. Food Funct. Green Chem. Inorg. Chem. Front. Integr. Biol. J. Anal. At. Spectrom. J. Mater. Chem. A J. Mater. Chem. B J. Mater. Chem. C Lab Chip Mater. Chem. Front. Mater. Horiz. MEDCHEMCOMM Metallomics Mol. Biosyst. Mol. Syst. Des. Eng. Nanoscale Nanoscale Horiz. Nat. Prod. Rep. New J. Chem. Org. Biomol. Chem. Org. Chem. Front. PHOTOCH PHOTOBIO SCI PCCP Polym. Chem.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:604180095
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1