Imre Bárány, Travis Dillon, Dömötör Pálvölgyi, Dániel Varga
{"title":"穿透相交凸集","authors":"Imre Bárány, Travis Dillon, Dömötör Pálvölgyi, Dániel Varga","doi":"arxiv-2409.06472","DOIUrl":null,"url":null,"abstract":"Assume two finite families $\\mathcal A$ and $\\mathcal B$ of convex sets in\n$\\mathbb{R}^3$ have the property that $A\\cap B\\ne \\emptyset$ for every $A \\in\n\\mathcal A$ and $B\\in \\mathcal B$. Is there a constant $\\gamma >0$ (independent\nof $\\mathcal A$ and $\\mathcal B$) such that there is a line intersecting\n$\\gamma|\\mathcal A|$ sets in $\\mathcal A$ or $\\gamma|\\mathcal B|$ sets in\n$\\mathcal B$? This is an intriguing Helly-type question from a paper by\nMart\\'{i}nez, Roldan and Rubin. We confirm this in the special case when all\nsets in $\\mathcal A$ lie in parallel planes and all sets in $\\mathcal B$ lie in\nparallel planes; in fact, all sets from one of the two families has a line\ntransversal.","PeriodicalId":501407,"journal":{"name":"arXiv - MATH - Combinatorics","volume":"3 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Piercing intersecting convex sets\",\"authors\":\"Imre Bárány, Travis Dillon, Dömötör Pálvölgyi, Dániel Varga\",\"doi\":\"arxiv-2409.06472\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Assume two finite families $\\\\mathcal A$ and $\\\\mathcal B$ of convex sets in\\n$\\\\mathbb{R}^3$ have the property that $A\\\\cap B\\\\ne \\\\emptyset$ for every $A \\\\in\\n\\\\mathcal A$ and $B\\\\in \\\\mathcal B$. Is there a constant $\\\\gamma >0$ (independent\\nof $\\\\mathcal A$ and $\\\\mathcal B$) such that there is a line intersecting\\n$\\\\gamma|\\\\mathcal A|$ sets in $\\\\mathcal A$ or $\\\\gamma|\\\\mathcal B|$ sets in\\n$\\\\mathcal B$? This is an intriguing Helly-type question from a paper by\\nMart\\\\'{i}nez, Roldan and Rubin. We confirm this in the special case when all\\nsets in $\\\\mathcal A$ lie in parallel planes and all sets in $\\\\mathcal B$ lie in\\nparallel planes; in fact, all sets from one of the two families has a line\\ntransversal.\",\"PeriodicalId\":501407,\"journal\":{\"name\":\"arXiv - MATH - Combinatorics\",\"volume\":\"3 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-09-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv - MATH - Combinatorics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/arxiv-2409.06472\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - MATH - Combinatorics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.06472","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Assume two finite families $\mathcal A$ and $\mathcal B$ of convex sets in
$\mathbb{R}^3$ have the property that $A\cap B\ne \emptyset$ for every $A \in
\mathcal A$ and $B\in \mathcal B$. Is there a constant $\gamma >0$ (independent
of $\mathcal A$ and $\mathcal B$) such that there is a line intersecting
$\gamma|\mathcal A|$ sets in $\mathcal A$ or $\gamma|\mathcal B|$ sets in
$\mathcal B$? This is an intriguing Helly-type question from a paper by
Mart\'{i}nez, Roldan and Rubin. We confirm this in the special case when all
sets in $\mathcal A$ lie in parallel planes and all sets in $\mathcal B$ lie in
parallel planes; in fact, all sets from one of the two families has a line
transversal.