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JOURNALS // Ufimskii Matematicheskii Zhurnal // Archive

Ufimsk. Mat. Zh., 2018 Volume 10, Issue 2, Pages 43–56 (Mi ufa431)

Influence of stratification on the groups of conformal transformations of pseudo-Riemannian orbifolds

N. I. Zhukova

National Research University Higher School of Economics, Bol'shaya Pecherskaya str. 25/12, 603155, Nizhny Novgorod, Russia

Abstract: We study the groups of conformal transformations of $n$-dimensional pseudo-Riemannian orbifolds $({\mathcal N},g)$ as $n\geq 3$. We extend the Alekseevskii method for studying conformal transformation groups of Riemannian manifolds to pseudo-Riemannian orbifolds. We show that a conformal pseudo-Riemannian geometry is induced on each stratum of such orbifold. Due to this, for $k\in\{0,1\}\cup\{3,\ldots,n-1\}$, we obtain exact estimates for the dimensions of the conformal transformation groups of $n$-dimensional pseudo-Riemannian orbifolds admitting $k$-dimensional stratum with essential groups of conformal transforms. A key fact in obtaining these estimates is that each connected transformation group of an orbifold preserves every connected component of each its stratum.
The influence of stratification of $n$-dimensional pseudo-Riemann orbifold to the similarity transformation group of this orbifold is also studied for $n\geq 2$.
We prove that the obtained estimates for the dimension of the complete essential groups of conformal transformations and the similarity transformation groups of $n$-dimensional pseudo-Riemann orbifolds are sharp; this is done by adducing corresponding examples of locally flat pseudo-Riemannian orbifolds.

Keywords: orbifold, conformal pseudo-Riemannian geometry, conformal transformation, Lie group.

UDC: 514.7

MSC: 53C50, 53A30

Received: 08.05.2017


 English version:
Ufa Mathematical Journal, 2018, 10:2, 44–57

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© Steklov Math. Inst. of RAS, 2025