encolado, pegado, ..., gluing
Buscando material de topología para la traducción lacaniana, encontré esto, via cmat.
Gluing is a good method to construct new topological spaces from known ones.
Here a rectangles is glued along the edges to form a torus.
Here a rectangles is glued along the edges to form a torus.
Often the fundamental group of the glued object can be calculated from the pieces (here a rectangles)
and the glue (here two intersecting circles).
The mathematical tool to do this is called the Seifert-van Kampen Theorem.
This Video was produces for a topology seminar at the Leibniz Universitaet Hannover.
http://www-ifm.math.uni-hannover.de/~...
This Video was produces for a topology seminar at the Leibniz Universitaet Hannover.
http://www-ifm.math.uni-hannover.de/~...
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Otro, buenísimo también:
http://www.youtube.com/watch?v=lDqmaPEjJpk
The projective plane is the space of lines through the origin in 3-space.
In the projective plane, we have the remarkable fact that
any two distinct lines meet in a unique point.
Moreover, we may not distinquish between
different kinds of smooth conic sections,
e.g. between an ellipse and a hyperbola,
as illustrated by the animation.
Notice that to each line through the origin correspond
Notice that to each line through the origin correspond
two antipodal points of a sphere
which is centered at the origin.
Instead of looking at the lines in total,
we may thus restrict ourselves to the points on the sphere.
Here, a line becomes a great circle and it is clear that
any two such circles meet in a unique pair of antipodal points.
Similarly, we may see that a hyperbola is projectively
the same thing as an ellipse.
Going back to the definition:
They are both just a cone in 3-space;
each line on the cone is one projective point
of the projective conic section.
This animation was made by Oliver Labs using surfex.
This animation was #3 on our geometric animations advent calendar:
http://www.calendar.algebraicsurface.net
This animation was made by Oliver Labs using surfex.
This animation was #3 on our geometric animations advent calendar:
http://www.calendar.algebraicsurface.net
Category: Howto & Style
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