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Klein bottle (Definition)

Where a Möbius strip is a two dimensional object with only one surface and one edge, a Klein bottle is a two dimensional object with a single surface, and no edges. Consider for comparison, that a sphere is a two dimensional surface with no edges, but that has two surfaces.

A Klein bottle can be constructed by taking a rectangular subset of $ \mathbb{R}^2$ and identifying opposite edges with each other, in the following fashion:

Consider the rectangular subset $ [-1,1] \times [-1,1]$. Identify the points $ (x, 1)$ with $ (x, -1)$, and the points $ (1,y)$ with the points $ (-1,-y)$. Doing these two operations simultaneously will give you the Klein bottle.

Visually, the above is accomplished by the following. Take a rectangle, and match up the arrows on the edges so that their orientation matches:

\includegraphics{klein.eps}

This of course is completely impossible to do physically in 3-dimensional space; to be able to properly create a Klein bottle, one would need to be able to build it in 4-dimensional space.

To construct a pseudo-Klein bottle in 3-dimensional space, you would first take a cylinder and cut a hole at one point on the side. Next, bend one end of the cylinder through that hole, and attach it to the other end of the clyinder.

A Klein bottle may be parametrized by the following equations:

$\displaystyle x$ $\displaystyle = \begin{cases}a\cos(u)\bigl(1+\sin(u)\bigr) + r\cos(u)\cos(v) & ... ... a\cos(u)\bigl(1+\sin(u)\bigr) + r\cos(v + \pi) & \pi < u \le 2\pi \end{cases}$    
$\displaystyle y$ $\displaystyle =\begin{cases}b\sin(u) + r\sin(u)\cos(v) & 0 \le u < \pi\ b\sin(u) & \pi < u \le 2\pi \end{cases}$    
$\displaystyle z$ $\displaystyle = r\sin(v)$    

where $ v\in [0,2\pi], u \in [0, 2\pi], r = c(1-\frac{\cos(u)}{2})$ and $ a, b, c$ are chosen arbitrarily.



"Klein bottle" is owned by vernondalhart.
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See Also: Möbius strip

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Cross-references: equations, side, cut, cylinder, orientation, rectangle, operations, points, opposite, subset, sphere, edge, surface, object, Möbius strip
There are 7 references to this entry.

This is version 9 of Klein bottle, born on 2003-05-07, modified 2006-07-17.
Object id is 4249, canonical name is KleinBottle.
Accessed 3481 times total.

Classification:
AMS MSC54B15 (General topology :: Basic constructions :: Quotient spaces, decompositions)

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