{"title":"环状刻划正方形的可循环链连续体","authors":"Ulises Morales-Fuentes , Cristina Villanueva-Segovia","doi":"10.1016/j.topol.2025.109379","DOIUrl":null,"url":null,"abstract":"<div><div>Let <em>A</em> denote the annulus <span><math><mo>{</mo><mi>x</mi><mo>∈</mo><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>:</mo><mn>1</mn><mo>≤</mo><mo>|</mo><mo>|</mo><mi>x</mi><mo>|</mo><mo>|</mo><mo>≤</mo><mn>1</mn><mo>+</mo><msqrt><mrow><mn>2</mn></mrow></msqrt><mo>}</mo></math></span>. In this paper we prove that if <em>X</em> is a circularly chainable continuum essentially embedded in <em>A</em>, then <em>X</em> contains the four vertices of an Euclidean square of side length at least <span><math><msqrt><mrow><mn>2</mn></mrow></msqrt></math></span>. Furthermore, let us say that a plane continuum <em>X</em> satisfies the property of annular inscription in <em>A</em> if whenever <em>X</em> is essentially embedded in <em>A</em>, the image of such embedding admits an inscribed square of side length at least <span><math><msqrt><mrow><mn>2</mn></mrow></msqrt></math></span>. We show that every circularly chainable, not chainable plane continuum satisfies the property of annular inscription in <em>A</em> and, moreover, that the property of annular inscription in <em>A</em> is generic among continua that separate the plane.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"368 ","pages":"Article 109379"},"PeriodicalIF":0.6000,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Circularly chainable continua that annularly inscribe squares\",\"authors\":\"Ulises Morales-Fuentes , Cristina Villanueva-Segovia\",\"doi\":\"10.1016/j.topol.2025.109379\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Let <em>A</em> denote the annulus <span><math><mo>{</mo><mi>x</mi><mo>∈</mo><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>:</mo><mn>1</mn><mo>≤</mo><mo>|</mo><mo>|</mo><mi>x</mi><mo>|</mo><mo>|</mo><mo>≤</mo><mn>1</mn><mo>+</mo><msqrt><mrow><mn>2</mn></mrow></msqrt><mo>}</mo></math></span>. In this paper we prove that if <em>X</em> is a circularly chainable continuum essentially embedded in <em>A</em>, then <em>X</em> contains the four vertices of an Euclidean square of side length at least <span><math><msqrt><mrow><mn>2</mn></mrow></msqrt></math></span>. Furthermore, let us say that a plane continuum <em>X</em> satisfies the property of annular inscription in <em>A</em> if whenever <em>X</em> is essentially embedded in <em>A</em>, the image of such embedding admits an inscribed square of side length at least <span><math><msqrt><mrow><mn>2</mn></mrow></msqrt></math></span>. We show that every circularly chainable, not chainable plane continuum satisfies the property of annular inscription in <em>A</em> and, moreover, that the property of annular inscription in <em>A</em> is generic among continua that separate the plane.</div></div>\",\"PeriodicalId\":51201,\"journal\":{\"name\":\"Topology and its Applications\",\"volume\":\"368 \",\"pages\":\"Article 109379\"},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2025-03-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Topology and its Applications\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0166864125001774\",\"RegionNum\":4,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Topology and its Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166864125001774","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
Circularly chainable continua that annularly inscribe squares
Let A denote the annulus . In this paper we prove that if X is a circularly chainable continuum essentially embedded in A, then X contains the four vertices of an Euclidean square of side length at least . Furthermore, let us say that a plane continuum X satisfies the property of annular inscription in A if whenever X is essentially embedded in A, the image of such embedding admits an inscribed square of side length at least . We show that every circularly chainable, not chainable plane continuum satisfies the property of annular inscription in A and, moreover, that the property of annular inscription in A is generic among continua that separate the plane.
期刊介绍:
Topology and its Applications is primarily concerned with publishing original research papers of moderate length. However, a limited number of carefully selected survey or expository papers are also included. The mathematical focus of the journal is that suggested by the title: Research in Topology. It is felt that it is inadvisable to attempt a definitive description of topology as understood for this journal. Certainly the subject includes the algebraic, general, geometric, and set-theoretic facets of topology as well as areas of interactions between topology and other mathematical disciplines, e.g. topological algebra, topological dynamics, functional analysis, category theory. Since the roles of various aspects of topology continue to change, the non-specific delineation of topics serves to reflect the current state of research in topology.
At regular intervals, the journal publishes a section entitled Open Problems in Topology, edited by J. van Mill and G.M. Reed. This is a status report on the 1100 problems listed in the book of the same name published by North-Holland in 1990, edited by van Mill and Reed.