{"title":"单位正方形和单位圆盘的不透明集合的显式下界","authors":"Markus Kiderlen, Florian Pausinger","doi":"10.1007/s10474-026-01606-x","DOIUrl":null,"url":null,"abstract":"<div><p>Explicit lower bounds for the length of the shortest opaque set for the unit disc and the unit square in the Euclidean plane are derived. The results are based on an explicit application of the general method of Kawamura, Moriyama, Otachi and Pach [9]. Employing a recent observation by Steinerberger on the possible orientations of straight barriers with length close to Jones’ bound, we improve the bound in [9] by more than a factor 3. The bound for barriers of the unit disc is new and based on the idea that the free parameters in the general method from [9] can be optimized due to the strong symmetry properties of the disc. Our approach illustrates both the power and the limitations of the method.</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"178 1","pages":"289 - 303"},"PeriodicalIF":0.6000,"publicationDate":"2026-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10474-026-01606-x.pdf","citationCount":"0","resultStr":"{\"title\":\"Explicit lower bounds for opaque sets of unit square and unit disc\",\"authors\":\"Markus Kiderlen, Florian Pausinger\",\"doi\":\"10.1007/s10474-026-01606-x\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Explicit lower bounds for the length of the shortest opaque set for the unit disc and the unit square in the Euclidean plane are derived. The results are based on an explicit application of the general method of Kawamura, Moriyama, Otachi and Pach [9]. Employing a recent observation by Steinerberger on the possible orientations of straight barriers with length close to Jones’ bound, we improve the bound in [9] by more than a factor 3. The bound for barriers of the unit disc is new and based on the idea that the free parameters in the general method from [9] can be optimized due to the strong symmetry properties of the disc. Our approach illustrates both the power and the limitations of the method.</p></div>\",\"PeriodicalId\":50894,\"journal\":{\"name\":\"Acta Mathematica Hungarica\",\"volume\":\"178 1\",\"pages\":\"289 - 303\"},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2026-05-13\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://link.springer.com/content/pdf/10.1007/s10474-026-01606-x.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Mathematica Hungarica\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s10474-026-01606-x\",\"RegionNum\":3,\"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":"Acta Mathematica Hungarica","FirstCategoryId":"100","ListUrlMain":"https://link.springer.com/article/10.1007/s10474-026-01606-x","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
Explicit lower bounds for opaque sets of unit square and unit disc
Explicit lower bounds for the length of the shortest opaque set for the unit disc and the unit square in the Euclidean plane are derived. The results are based on an explicit application of the general method of Kawamura, Moriyama, Otachi and Pach [9]. Employing a recent observation by Steinerberger on the possible orientations of straight barriers with length close to Jones’ bound, we improve the bound in [9] by more than a factor 3. The bound for barriers of the unit disc is new and based on the idea that the free parameters in the general method from [9] can be optimized due to the strong symmetry properties of the disc. Our approach illustrates both the power and the limitations of the method.
期刊介绍:
Acta Mathematica Hungarica is devoted to publishing research articles of top quality in all areas of pure and applied mathematics as well as in theoretical computer science. The journal is published yearly in three volumes (two issues per volume, in total 6 issues) in both print and electronic formats. Acta Mathematica Hungarica (formerly Acta Mathematica Academiae Scientiarum Hungaricae) was founded in 1950 by the Hungarian Academy of Sciences.