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Difference between revisions of "Normal space (to a surface)"

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''at a point <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676701.png" />''
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''at a point $P$''
  
The orthogonal complement <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676702.png" /> to the tangent space <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676703.png" /> (see [[Tangent plane|Tangent plane]]) of the surface <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676704.png" /> in <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676705.png" /> at <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676706.png" />. The dimension of the normal space is <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676707.png" /> (the codimension of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676708.png" />). Every one-dimensional subspace of it is called a [[Normal|normal]] to <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n0676709.png" /> at <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n06767010.png" />. If <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n067/n067670/n06767011.png" /> is a smooth hypersurface, then it has a unique normal at every of its points.
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The orthogonal complement $N_PF$ to the tangent space $T_PF$ (see [[Tangent plane|Tangent plane]]) of the surface $F^m$ in $V^n$ at $P$. The dimension of the normal space is $n-m$ (the codimension of $F$). Every one-dimensional subspace of it is called a [[Normal|normal]] to $F$ at $P$. If $F$ is a smooth hypersurface, then it has a unique normal at every of its points.
  
  

Latest revision as of 17:17, 30 July 2014

at a point $P$

The orthogonal complement $N_PF$ to the tangent space $T_PF$ (see Tangent plane) of the surface $F^m$ in $V^n$ at $P$. The dimension of the normal space is $n-m$ (the codimension of $F$). Every one-dimensional subspace of it is called a normal to $F$ at $P$. If $F$ is a smooth hypersurface, then it has a unique normal at every of its points.


Comments

References

[a1] W. Klingenberg, "Riemannian geometry" , de Gruyter (1982) (Translated from German)
[a2] B.-Y. Chen, "Geometry of submanifolds" , M. Dekker (1973)
How to Cite This Entry:
Normal space (to a surface). Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Normal_space_(to_a_surface)&oldid=17490
This article was adapted from an original article by A.B. Ivanov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article