🌐EnglishEnglishEspañolFrançaisNederlandsPortuguêsРусскийالعربيةفارسیไทย한국어中文日本語EntityQ1033772· pop 17· linked from 20 articlesHappy Ending problemproblem about proving that five points in the plane will have a subset forming the vertices of a convex quadrilateralWikidata factsImageHappy-End-problem.svgSources (1)wikidata.orgvia Wikidata · CC0Available in 17 languagesEspañolFrançais中文РусскийPortuguêsItalianoالعربيةCatalanFinnishGreekConnectionsmathematicsEntitytriangleEntityCategoriesDiscrete geometryEuclidean plane geometryMathematical problemsPaul ErdősPolygonsQuadrilateralsRamsey theory