A következő címkéjű bejegyzések mutatása: archiv. Összes bejegyzés megjelenítése
A következő címkéjű bejegyzések mutatása: archiv. Összes bejegyzés megjelenítése
2010. január 15., péntek
The Alexander Sphere
A path that is homoemorphic to a circle devides a compactified plane into two pieces (inside and outside). Arthur Schönflies proved in 1906 that in this situation the inside and outside are homoemorphic.
To prove a similar statement in 3 dimensions was an open problem for many years. It was solved by James Alexander in 1928 who constructed the Alexander "Horned" Sphere, as illustrated in this video. The Alexander horned sphere is a topological space which is homeomorphic to a sphere, but inside and outside are not homeomorphic. This proves that there is no analog of Schönflies Theorem in three dimensions.
This Video was produces for a topology seminar at the Leibniz Universitaet Hannover.
http://www-ifm.math.uni-hannover.de/~...
This animation was #1 on our geometric animations advent calendar:
http://www.calendar.algebraicsurface.net
2009. július 27., hétfő
Orignal Batman Clips (fight scenes)
Orignal Batman Clips (fight scenes)
a few clips of the original batman scenes, possibly one of the greatest shows of all time , well maybe http://www.youtube.com/watch?v=k7_7semtxI0&feature=related
a few clips of the original batman scenes, possibly one of the greatest shows of all time , well maybe http://www.youtube.com/watch?v=k7_7semtxI0&feature=related
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