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Difference between revisions of "Barycentric subdivision"

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''of a geometric complex <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152901.png" />''
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''of a geometric complex $K$''
  
A complex <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152902.png" /> obtained by replacing the simplices of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152903.png" /> by smaller ones by means of the following procedure. Each one-dimensional simplex (segment) is halved. On the assumption that all simplices of dimension <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152904.png" /> are already subdivided, the subdivision of any <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152905.png" />-dimensional simplex <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152906.png" /> is defined by means of cones over the simplices of the boundary of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152907.png" /> with a common vertex that is the barycentre of the simplex <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152908.png" />, i.e. the point with [[Barycentric coordinates|barycentric coordinates]] <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b0152909.png" />. The vertices of the resulting complex <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b01529010.png" /> are in a one-to-one correspondence with the simplices of the complex <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b01529011.png" />, while the simplices of the complex <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b01529012.png" /> are in such a correspondence with inclusion-ordered finite tuples of simplices from <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/b/b015/b015290/b01529013.png" />. The formal definition of a barycentric subdivision for the case of an abstract complex is analogous.
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A complex $K_1$ obtained by replacing the simplices of $K$ by smaller ones by means of the following procedure. Each one-dimensional simplex (segment) is halved. On the assumption that all simplices of dimension $\leq n-1$ are already subdivided, the subdivision of any $n$-dimensional simplex $\sigma$ is defined by means of cones over the simplices of the boundary of $\sigma$ with a common vertex that is the barycentre of the simplex $\sigma$, i.e. the point with [[Barycentric coordinates|barycentric coordinates]] $1/(n+1)$. The vertices of the resulting complex $K_1$ are in a one-to-one correspondence with the simplices of the complex $K$, while the simplices of the complex $K_1$ are in such a correspondence with inclusion-ordered finite tuples of simplices from $K$. The formal definition of a barycentric subdivision for the case of an abstract complex is analogous.
  
  

Revision as of 16:20, 15 April 2014

of a geometric complex $K$

A complex $K_1$ obtained by replacing the simplices of $K$ by smaller ones by means of the following procedure. Each one-dimensional simplex (segment) is halved. On the assumption that all simplices of dimension $\leq n-1$ are already subdivided, the subdivision of any $n$-dimensional simplex $\sigma$ is defined by means of cones over the simplices of the boundary of $\sigma$ with a common vertex that is the barycentre of the simplex $\sigma$, i.e. the point with barycentric coordinates $1/(n+1)$. The vertices of the resulting complex $K_1$ are in a one-to-one correspondence with the simplices of the complex $K$, while the simplices of the complex $K_1$ are in such a correspondence with inclusion-ordered finite tuples of simplices from $K$. The formal definition of a barycentric subdivision for the case of an abstract complex is analogous.


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References

[a1] K. Lamotke, "Semisimpliziale algebraische Topologie" , Springer (1968)
How to Cite This Entry:
Barycentric subdivision. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Barycentric_subdivision&oldid=31751
This article was adapted from an original article by E.G. Sklyarenko (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article