🌐EnglishEnglishEspañolFrançaisItalianoNederlandsPortuguêsРусский日本語EntityQ390518· pop 9· linked from 48 articlesIllumination problemmathematical problemWikidata factsImagePenrose unilluminable room.svgSources (1)wikidata.orgvia Wikidata · CC0Available in 8 languagesEspañolFrançais日本語РусскийPortuguêsItalianoCatalanvia Wikidata sitelinks · CC0ConnectionsYouTubeConceptStephen HawkingPersonmirrorCategoriesDynamical systemsMathematical problemsReflection (mathematics)