🌐EnglishEnglishEspañolNederlandsPolskiPortuguêsРусский한국어日本語EntityQ2436606· pop 9· linked from 24 articlesexotic R4A smooth 4-manifold homeomorphic yet not diffeomorphic to euclidean spaceConnectionsClifford TaubesEntitymathematicsEntityCategories4-manifoldsDifferential structures