Difference between revisions 107880288 and 107880289 on dewiki

[[Image:Alexander horned sphere.png|thumb|300px|right|Alexander horned sphere]]

The '''Alexander horned sphere''' is one of the most famous [[pathological (mathematics)|pathological example]]s in [[mathematics]], discovered in 1924 by [[James Waddell Alexander II|J. W. Alexander]] by {{harvs|txt|authorlink=James Waddell Alexander II|first=J. W. |last=Alexander|year=1924}}. It is the particular [[embedding (topology)|embedding]] of a [[sphere]] in 3-dimensional [[Euclidean space]] obtained by the following construction, starting with a [[standard torus]]:
#Remove a radial slice of the torus.
#Connect a standard punctured torus to each side of the cut, interlinked with the torus on the other side.
#Repeat steps 1–3 on the two tori just added ''ad infinitum''.
(contracted; show full)
[[ca:Esfera banyada d'Alexander]]
[[es:Esfera cornuda de Alexander]]
[[fr:Sphère cornue d'Alexander]]
[[ko:알렉산더의 뿔 달린 구]]
[[it:Sfera di Alexander]]
[[pl:Rogata sfera Alexandera]]
[[ru:Дикая сфера]]