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Vestnik Volgogradskogo gosudarstvennogo universiteta. Seriya 1. Mathematica. Physica, 2014, Issue 2(21), Pages 6–16
(Mi vvgum41)
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Mathematics
Some properties of normal sections and geodesics
on cyclic recurrent submanifolds
I. I. Bodrenko Volgograd State University
Abstract:
Let $F^{n}$ be $n$-dimensional $(n \geq 2)$ submanifold in
$(n+p)$-dimensional Euclidean space $E^{n+p}$ $(p \geq 1)$. Let
$x$ be arbitrary point $F^n$, $T_xF^n$ be tangent space to $F^n$
at the point $x$. Let $\gamma_g(x, t)$ be a geodesic on $F^n$
passing through the point $x\in F^n$ in the direction $t\in T_x
F^n$. Denote by $k_g (x, t)$ and $\varkappa_g (x, t)$ curvature
and torsion of geodesic $\gamma_g (x, t)\subset E^{n+p}$,
respectively, calculated for point $x$.
Torsion $\varkappa_g(x, t)$ of geodesic $\gamma_g (x, t)$ is
called geodesic torsion of submanifold $F^n\subset E^{n+p}$ at the
point $x$ in the direction $t$.
Let $\gamma_N(x, t)$ be a normal section of submanifold
$F^n\subset E^{n+p}$ at the point $x\in F^n$ in the direction
$t\in T_xF^n$. Denote by $k_N (x, t)$ and $\varkappa_N (x, t)$
curvature and torsion of normal section $\gamma_N (x, t)\subset
E^{n+p}$, respectively, calculated for point $x$.
Denote by $b$ the second fundamental form of $F^n$, by
$\overline\nabla$ the connection of van der Waerden — Bortolotti.
The fundamental form $b\not=0$ is called cyclic recurrent if on
$F^n$ there exists $1$-form $\mu$ such that
$$
\overline\nabla_X b(Y,Z)= \mu(X)b(Y,Z) + \mu(Y)b(Z,X)+
\mu(Z)b(X,Y)
$$
for all vector fields $X, Y, Z$ tangent to $F^n$.
Submanifold $F^n\subset E^{n+p}$ with cyclic recurrent the second
fundamental form $b\ne 0$ is called cyclic recurrent submanifold.
The properties of normal sections $\gamma_N(x, t)$ and
geodesics $\gamma_g(x, t)$ on cyclic recurrent submanifolds
$F^n\subset E^{n+p}$ are studied in this article. The conditions
for which cyclic recurrent submanifolds $F^n \subset E^{n+p}$
have zero geodesic torsion $\varkappa_g(x, t)\equiv 0$ at
every point $x\in F^n$ in every direction $t\in T_xF^n$ are
derived in this article.
Denote by ${\mathcal R}_0$ a set of submanifolds $F^n\subset E^{n+p}$,
on which
$$
k_g (x,t)\ne 0, \quad \varkappa_g(x,t)\equiv 0, \quad \forall x\in
F^n, \quad \forall t\in T_xF^n.
$$
The following theorem is proved in this article.
Let $F^n$ be a cyclic recurrent submanifold in $E^{n+p}$ with no
asymptotic directions. Then $F^n$ belongs to the set ${\mathcal R}_0$
if and only if the following condition holds:
$$
k_N(x, t) = k(x), \quad \forall x\in F^n, \quad \forall t\in
T_xF^n.
$$
Keywords:
the second fundamental form, cyclic recurrent submanifold, geodesic torsion, normal section, normal
curvature, normal torsion, connection of van der Waerden — Bortolotti.
Citation:
I. I. Bodrenko, “Some properties of normal sections and geodesics
on cyclic recurrent submanifolds”, Vestnik Volgogradskogo gosudarstvennogo universiteta. Seriya 1. Mathematica. Physica, 2014, no. 2(21), 6–16
Linking options:
https://www.mathnet.ru/eng/vvgum41 https://www.mathnet.ru/eng/vvgum/y2014/i2/p6
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