Source: J. Math. Soc. Japan Volume 61, Number 2
(2009), 437-481.
An austere submanifold is a minimal submanifold where for each normal vector, the set of eigenvalues of its shape operator is invariant under the multiplication by $-1$. In the present paper, we introduce the notion of weakly reflective submanifold, which is an austere submanifold with a reflection for each normal direction, and study its fundamental properties. Using these, we determine weakly reflective orbits and austere orbits of linear isotropy representations of Riemannian symmetric spaces.
References
L. Bérard-Bergery, Sur de nouvelles variétés riemanniennes d'Einstein, Inst. Élie. Cartan, 6 (1982), 1–60.
V. Borrelli and C. Gorodski, Minimal Legendrian submanifolds of $S^{2n+1}$ and absolutely area-minimizing cones, Differential Geom. Appl., 21 (2004), 337–347.
N. Bourbaki, Groupes et algebres de Lie, Hermann, Paris, 1975.
Mathematical Reviews (MathSciNet):
MR453824
R. Harvey and H. B. Lawson, Jr., Calibrated geometries, Acta Math., 148 (1982), 47–157.
Mathematical Reviews (MathSciNet):
MR666108
S. Helgason, Differential geometry, Lie groups, and symmetric spaces, Academic Press, New York, 1978.
Mathematical Reviews (MathSciNet):
MR514561
D. Hirohashi, T. Kanno and H. Tasaki, Area-minimizing of the cone over symmetric $R$-spaces, Tsukuba J. Math., 24 (2000), 171–188.
D. Hirohashi, H. Song, R. Takagi and H. Tasaki, Minimal orbits of the isotropy groups of symmetric spaces of compact type, Differential Geom. Appl., 13 (2000), 167–177.
A. Kollross, A classification of hyperpolar and cohomogeneity one actions, Trans. Amer. Math. Soc., 354 (2002), 571–612.
Dominic S. P. Leung, The reflection principle for minimal submanifolds of Riemannian symmetric spaces, J. Differential Geometry, 8 (1973), 153–160.
Mathematical Reviews (MathSciNet):
MR367872
P. S. Mostert, On a compact Lie group acting on a manifold, Ann. of Math. (2), 65 (1957), 447–455.
Mathematical Reviews (MathSciNet):
MR85460
R. Palais and C.-L. Terng, A general theory of canonical forms, Trans. Amer. Math. Soc., 300 (1987), 771–789.
Mathematical Reviews (MathSciNet):
MR876478
R. Palais and C.-L. Terng, Critical point theory and submanifold geometry, Lecture Notes in Mathematics 1353, Springer, 1988.
Mathematical Reviews (MathSciNet):
MR972503
F. Podestà, Some remarks on austere submanifolds, Boll. Un. Mat. Ital. B(7), 11 (1997), no. 2, suppl., 157–160.
M. Takeuchi, Modern spherical functions, Translations of Mathematical Monographs, 135, American Mathematical Society, Providence, RI, 1994.