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Difference between revisions of "Nil manifold"

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A compact quotient space of a connected nilpotent Lie group (cf. [[Lie group, nilpotent|Lie group, nilpotent]]). (However, sometimes compactness is not required.)
 
A compact quotient space of a connected nilpotent Lie group (cf. [[Lie group, nilpotent|Lie group, nilpotent]]). (However, sometimes compactness is not required.)
  
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Cf. also [[Nil flow|Nil flow]] and the references quoted there.
 
Cf. also [[Nil flow|Nil flow]] and the references quoted there.
  
An example of a nil manifold that is rather important for various applications is the following. Consider the three-dimensional Heisenberg group <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666801.png" /> of all matrices of the form
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An example of a nil manifold that is rather important for various applications is the following. Consider the three-dimensional Heisenberg group $N$ of all matrices of the form
  
<table class="eq" style="width:100%;"> <tr><td valign="top" style="width:94%;text-align:center;"><img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666802.png" /></td> </tr></table>
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$$\begin{pmatrix}1&y&z\\0&1&x\\0&0&1\end{pmatrix}$$
  
and the discrete subgroup <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666803.png" /> of all such matrices with integer <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666804.png" />, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666805.png" />, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666806.png" />. The corresponding quotient space <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666807.png" /> of cosets <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666808.png" />, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/n/n066/n066680/n0666809.png" />, is a compact nil manifold with an invariant probability measure. It plays an important role in harmonic analysis and the theory of theta-functions.
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and the discrete subgroup $\Gamma$ of all such matrices with integer $x$, $y$, $z$. The corresponding quotient space $\Gamma\setminus N$ of cosets $\Gamma n$, $n\in N$, is a compact nil manifold with an invariant probability measure. It plays an important role in harmonic analysis and the theory of theta-functions.
  
 
====References====
 
====References====
 
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  L. Auslander,  "Lecture notes on nil-theta functions" , Amer. Math. Soc.  (1977)</TD></TR></table>
 
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  L. Auslander,  "Lecture notes on nil-theta functions" , Amer. Math. Soc.  (1977)</TD></TR></table>

Latest revision as of 15:48, 10 July 2014

A compact quotient space of a connected nilpotent Lie group (cf. Lie group, nilpotent). (However, sometimes compactness is not required.)

References

[1] A.I. Mal'tsev, "On a class of homogeneous spaces" Transl. Amer. Math. Soc. (1) , 9 (1962) pp. 276–307 Izv. Akad. Nauk SSSR Ser. Mat. , 13 : 1 (1949) pp. 9–32


Comments

Cf. also Nil flow and the references quoted there.

An example of a nil manifold that is rather important for various applications is the following. Consider the three-dimensional Heisenberg group $N$ of all matrices of the form

$$\begin{pmatrix}1&y&z\\0&1&x\\0&0&1\end{pmatrix}$$

and the discrete subgroup $\Gamma$ of all such matrices with integer $x$, $y$, $z$. The corresponding quotient space $\Gamma\setminus N$ of cosets $\Gamma n$, $n\in N$, is a compact nil manifold with an invariant probability measure. It plays an important role in harmonic analysis and the theory of theta-functions.

References

[a1] L. Auslander, "Lecture notes on nil-theta functions" , Amer. Math. Soc. (1977)
How to Cite This Entry:
Nil manifold. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Nil_manifold&oldid=19191
This article was adapted from an original article by D.V. Anosov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article