{"title":"在投影闭合曲线的重切线上","authors":"Thomas Blomme","doi":"10.1112/blms.70061","DOIUrl":null,"url":null,"abstract":"<p>We generalize a previous result by Fabricius–Bjerre [Math. Scand. 11 (1962), no. 2, 113–116] from curves in <span></span><math>\n <semantics>\n <msup>\n <mi>R</mi>\n <mn>2</mn>\n </msup>\n <annotation>$\\mathbb {R}^2$</annotation>\n </semantics></math> to curves in <span></span><math>\n <semantics>\n <mrow>\n <mi>R</mi>\n <msup>\n <mi>P</mi>\n <mn>2</mn>\n </msup>\n </mrow>\n <annotation>$\\mathbb {R}P^2$</annotation>\n </semantics></math>. Applied to the case of real algebraic curves, this recovers the signed count of bitangents of quartics introduced by Larson–Vogt [Res. Math. Sci. 8 (2021), no. 26] and proves its positivity, conjectured by Larson–Vogt. Our method is not specific to quartics and applies to algebraic curves of any degree.</p>","PeriodicalId":55298,"journal":{"name":"Bulletin of the London Mathematical Society","volume":"57 6","pages":"1791-1800"},"PeriodicalIF":0.9000,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On the double tangent of projective closed curves\",\"authors\":\"Thomas Blomme\",\"doi\":\"10.1112/blms.70061\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>We generalize a previous result by Fabricius–Bjerre [Math. Scand. 11 (1962), no. 2, 113–116] from curves in <span></span><math>\\n <semantics>\\n <msup>\\n <mi>R</mi>\\n <mn>2</mn>\\n </msup>\\n <annotation>$\\\\mathbb {R}^2$</annotation>\\n </semantics></math> to curves in <span></span><math>\\n <semantics>\\n <mrow>\\n <mi>R</mi>\\n <msup>\\n <mi>P</mi>\\n <mn>2</mn>\\n </msup>\\n </mrow>\\n <annotation>$\\\\mathbb {R}P^2$</annotation>\\n </semantics></math>. Applied to the case of real algebraic curves, this recovers the signed count of bitangents of quartics introduced by Larson–Vogt [Res. Math. Sci. 8 (2021), no. 26] and proves its positivity, conjectured by Larson–Vogt. Our method is not specific to quartics and applies to algebraic curves of any degree.</p>\",\"PeriodicalId\":55298,\"journal\":{\"name\":\"Bulletin of the London Mathematical Society\",\"volume\":\"57 6\",\"pages\":\"1791-1800\"},\"PeriodicalIF\":0.9000,\"publicationDate\":\"2025-04-02\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Bulletin of the London Mathematical Society\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://londmathsoc.onlinelibrary.wiley.com/doi/10.1112/blms.70061\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin of the London Mathematical Society","FirstCategoryId":"100","ListUrlMain":"https://londmathsoc.onlinelibrary.wiley.com/doi/10.1112/blms.70061","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
We generalize a previous result by Fabricius–Bjerre [Math. Scand. 11 (1962), no. 2, 113–116] from curves in to curves in . Applied to the case of real algebraic curves, this recovers the signed count of bitangents of quartics introduced by Larson–Vogt [Res. Math. Sci. 8 (2021), no. 26] and proves its positivity, conjectured by Larson–Vogt. Our method is not specific to quartics and applies to algebraic curves of any degree.