{"title":"The structure of solid analytic FK-AK spaces","authors":"Beatriz Zamora-Aviles","doi":"10.1016/j.topol.2025.109579","DOIUrl":"10.1016/j.topol.2025.109579","url":null,"abstract":"<div><div>We study analytic, solid sequence spaces <em>λ</em> satisfying <span><math><msub><mrow><mi>c</mi></mrow><mrow><mn>00</mn></mrow></msub><mo>⊆</mo><mi>λ</mi><mo>⊆</mo><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>∞</mo></mrow></msup></math></span>. We prove that if <em>λ</em> contains an element with full support, and any countable subset of the positive cone <span><math><msup><mrow><mi>λ</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span> is eventually dominated pointwise by a single element in <span><math><msup><mrow><mi>λ</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>, then <em>λ</em> admits an <em>F</em>-norm, making it into an FK space with the AK property. This characterization closely parallels S. Solecki's well known characterization of analytic P-ideals of subsets of the natural numbers. Additionally, we provide a general method to construct FK spaces with the AK property from an additive sequence of closed subsets of the positive cone of <span><math><msup><mrow><mi>R</mi></mrow><mrow><mi>N</mi></mrow></msup></math></span>. Our results reveal that analytic P-ideals can be viewed as a discrete analogue of FK spaces with the AK property.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109579"},"PeriodicalIF":0.5,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048492","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}
{"title":"Few operators on Banach spaces C0(L × L)","authors":"Leandro Candido","doi":"10.1016/j.topol.2025.109577","DOIUrl":"10.1016/j.topol.2025.109577","url":null,"abstract":"<div><div>Using Ostaszewski's ♣-principle, we construct a non-metrizable, locally compact, scattered space <em>L</em> in which the operators on the Banach space <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>(</mo><mi>L</mi><mo>×</mo><mi>L</mi><mo>)</mo></math></span> exhibit a remarkably simple structure. We provide a detailed analysis and, through a series of decomposition steps, offer an explicit characterization of all operators on <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>(</mo><mi>L</mi><mo>×</mo><mi>L</mi><mo>)</mo></math></span>.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109577"},"PeriodicalIF":0.5,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095651","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}
{"title":"Alexander's theorem for stabilizer subgroups of Thompson's group","authors":"Yuya Kodama , Akihiro Takano","doi":"10.1016/j.topol.2025.109576","DOIUrl":"10.1016/j.topol.2025.109576","url":null,"abstract":"<div><div>In 2017, Jones studied the unitary representations of Thompson's group <em>F</em> and defined a method to construct knots and links from <em>F</em>. One of his results is that any knot or link can be obtained from an element of this group, which is called Alexander's theorem. On the other hand, even though Thompson's group <em>F</em> has many subgroups, only a few of them are known to satisfy or not satisfy Alexander's theorem. In this paper, we prove that almost all stabilizer subgroups under the natural action on the unit interval satisfy Alexander's theorem.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109576"},"PeriodicalIF":0.5,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095650","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}
{"title":"Higher topological complexity of planar polygon spaces having small genetic codes","authors":"Sutirtha Datta, Navnath Daundkar, Abhishek Sarkar","doi":"10.1016/j.topol.2025.109575","DOIUrl":"10.1016/j.topol.2025.109575","url":null,"abstract":"<div><div>We study the higher (sequential) topological complexity, a numerical homotopy invariant for the planar polygon spaces. For these spaces with a small genetic codes and dimension <em>m</em>, Davis showed that their topological complexity is either 2<em>m</em> or <span><math><mn>2</mn><mi>m</mi><mo>+</mo><mn>1</mn></math></span>. We extend these bounds to the setting of higher topological complexity. In particular, when <em>m</em> is power of 2, we show that the <em>k</em>-th higher topological complexity of these spaces is either <em>km</em> or <span><math><mi>k</mi><mi>m</mi><mo>+</mo><mn>1</mn></math></span>.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109575"},"PeriodicalIF":0.5,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145026318","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}
Jeffrey T. Denniston , Stephen E. Rodabaugh , Jamal K. Tartir
{"title":"Preservation and reflection of separation axioms by essentially Kolmogorov and Kolmogorov relations","authors":"Jeffrey T. Denniston , Stephen E. Rodabaugh , 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":"2025-09-03","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}
{"title":"Topological representations of bornological spaces and coercive maps","authors":"Gerald Beer , Homeira Pajoohesh","doi":"10.1016/j.topol.2025.109573","DOIUrl":"10.1016/j.topol.2025.109573","url":null,"abstract":"<div><div>We exhibit the duality between bornological spaces and a certain class of topological spaces of independent interest: the topological spaces of the cofinite type. The usual way to make the bornological spaces a category <strong>Bor</strong> is to take for morphisms bornological maps <span><span>[9]</span></span>. If we instead take coercive maps as discussed in <span><span>[5]</span></span> as morphisms, we obtain a very different category <strong>Bor</strong><sup>⁎</sup> that is isomorphic to the category of topological spaces of the cofinite type equipped with continuous maps as morphisms. We introduce a bornology on the bornological maps bor<span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>Y</mi><mo>)</mo></math></span> between bornological spaces <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>B</mi><mo>)</mo></math></span> and <span><math><mo>(</mo><mi>Y</mi><mo>,</mo><mi>C</mi><mo>)</mo></math></span>. Membership of <span><math><mi>E</mi><mo>⊆</mo><mtext>bor</mtext><mo>(</mo><mi>X</mi><mo>,</mo><mi>Y</mi><mo>)</mo></math></span> to this bornology means that the bornological maps in <em>E</em> are subject to a uniform growth bound. This growth bound can be expressed in terms of an expansion modulus, i.e., an increasing function between <span><math><mi>B</mi></math></span> and <span><math><mi>C</mi></math></span> mapping nonempty members of <span><math><mi>B</mi></math></span> to nonempty members of <span><math><mi>C</mi></math></span>. We introduce a parallel bornology on the coercive maps cocv<span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>Y</mi><mo>)</mo></math></span> between the bornological spaces as well. Notably, evaluation as defined on bor<span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>Y</mi><mo>)</mo><mo>×</mo><mi>X</mi></math></span> is a bornological map, whereas evaluation may fail to be a coercive map on cocv<span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>Y</mi><mo>)</mo><mo>×</mo><mi>X</mi></math></span>.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109573"},"PeriodicalIF":0.5,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019456","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}
{"title":"Reflexive group topologies on the integers generated by sequences - Part II","authors":"Lydia Außenhofer","doi":"10.1016/j.topol.2025.109572","DOIUrl":"10.1016/j.topol.2025.109572","url":null,"abstract":"<div><div>We characterize those <em>D</em>-sequences <strong>b</strong> in <span><math><mi>Z</mi></math></span> for which <span><math><mo>(</mo><mi>Z</mi><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>)</mo></math></span> is reflexive and show that for every <em>D</em>-sequence <strong>b</strong> the character group of <span><math><mo>(</mo><mi>Z</mi><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi></mrow></msub><mo>)</mo></math></span> is reflexive.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109572"},"PeriodicalIF":0.5,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019457","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}
{"title":"Strongly topologically orderable gyrogroups with a suitable set","authors":"Jiamin He , Jiajia Yang , Fucai Lin","doi":"10.1016/j.topol.2025.109565","DOIUrl":"10.1016/j.topol.2025.109565","url":null,"abstract":"<div><div>A discrete subset <em>S</em> of a topologically gyrogroup <em>G</em> is called a <em>suitable set</em> for <em>G</em> if <span><math><mi>S</mi><mo>∪</mo><mo>{</mo><mn>1</mn><mo>}</mo></math></span> is closed and the subgyrogroup generated by <em>S</em> is dense in <em>G</em>, where 1 is the identity element of <em>G</em>. In this paper, we mainly study the existence of suitable set of strongly topologically orderable gyrogroups, which extends some result in some papers in the literature. In particular, the existences of suitable set of each locally compact or not totally disconnected strongly topologically orderable gyrogroup are affirmative.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109565"},"PeriodicalIF":0.5,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996827","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}
{"title":"Chaos of trajectories","authors":"Seif Mezzi , Khadija Ben Rejeb","doi":"10.1016/j.topol.2025.109571","DOIUrl":"10.1016/j.topol.2025.109571","url":null,"abstract":"<div><div>Let <em>f</em> be a continuous self-map of a compact metric space <em>X</em>. Let <span><math><mi>O</mi><mo>(</mo><mi>f</mi><mo>)</mo></math></span> be the set of all trajectories under <em>f</em>, and let <em>T</em> denote its closure in the hyperspace <span><math><mi>K</mi><mo>(</mo><mi>X</mi><mo>)</mo></math></span> of all nonempty closed subsets of <em>X</em> equipped with the Hausdorff metric. The map <em>f</em> induces in a natural way a self-map <span><math><mover><mrow><mi>f</mi></mrow><mrow><mo>¯</mo></mrow></mover></math></span> on the space <em>T</em>. In this paper, we study transitivity, sensitivity, and chaos for the induced system <span><math><mo>(</mo><mi>T</mi><mo>,</mo><mover><mrow><mi>f</mi></mrow><mrow><mo>¯</mo></mrow></mover><mo>)</mo></math></span>. While we prove that this latter system can never be Devaney chaotic, we provide an example of a system <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>f</mi><mo>)</mo></math></span> for which the associated induced system <span><math><mo>(</mo><mi>T</mi><mo>,</mo><mover><mrow><mi>f</mi></mrow><mrow><mo>¯</mo></mrow></mover><mo>)</mo></math></span> is sensitive. We study which properties are inherited between the base system <span><math><mo>(</mo><mi>X</mi><mo>,</mo><mi>f</mi><mo>)</mo></math></span> and its induced system <span><math><mo>(</mo><mi>T</mi><mo>,</mo><mover><mrow><mi>f</mi></mrow><mrow><mo>¯</mo></mrow></mover><mo>)</mo></math></span>. We prove that several known results on the hyperspaces fail to be true on the spaces of trajectories.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109571"},"PeriodicalIF":0.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996825","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}
{"title":"Lie group concepts for S7 and its space of commuting elements","authors":"Jerry Wei","doi":"10.1016/j.topol.2025.109570","DOIUrl":"10.1016/j.topol.2025.109570","url":null,"abstract":"<div><div>The unit octonions, <span><math><msup><mrow><mi>S</mi></mrow><mrow><mn>7</mn></mrow></msup></math></span>, is an H-space which is not a Lie group due to failure of associativity. We examine the extent to which <span><math><msup><mrow><mi>S</mi></mrow><mrow><mn>7</mn></mrow></msup></math></span> has analogies of Lie group concepts such as maximal torus, Weyl group, Lie algebra, and exponential map. Moreover, we present a method for calculating the homology of the space of commuting <em>n</em>-tuples in <span><math><msup><mrow><mi>S</mi></mrow><mrow><mn>7</mn></mrow></msup></math></span> by induction on <em>n</em>.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109570"},"PeriodicalIF":0.5,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988868","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}