On a problem of Osserman in Lorentzian geometry

GarciaRio, E
Kupeli, DN
VazquezAbal, ME
A problem of Osserman on the constancy of the eigenvalues of the Jacobi operator is studied in Lorentzian geometry. Attention is paid to the different cases of timelike, spacelike and null Osserman condition. One also shows a relation between the null Osserman condition and a previous one on infinitesimal null isotropy.


BASKAL, S; ERIS, A; SATIR, A (1994-12-19)
The symmetries and associated conservation laws of the SO(2,1) invariant non-linear sigma model equations in 1+1 dimensions are investigated. An infinite family of generalized local symmetries is presented and the uniqueness of these solutions is discussed.
A note on the Gauss maps of Cayley-free embeddings into spin(7)-manifolds
Ünal, İbrahim (Elsevier BV, 2018-12-01)
We show that a closed, orientable 4-manifold M admits a Cayley-free embedding into flat Spin(7)-manifold R-8 if and only if both the Euler characteristic chi(M) and the signature tau(M) of M vanish.
On Stability of Linear Delay Differential Equations under Perron's Condition
Diblík, J.; Zafer, A. (Hindawi Limited, 2011)
The stability of the zero solution of a system of first-order linear functional differential equations with nonconstant delay is considered. Sufficient conditions for stability, uniform stability, asymptotic stability, and uniform asymptotic stability are established.
On homotopy groups of real algebraic varieties and their complexifications
Ozan, Yıldıray (Springer Science and Business Media LLC, 2004-10-01)
Let X-0 be a topological component of a nonsingular real algebraic variety and i : X --> X-C is a nonsingular projective complexification of X. In this paper, we will study the homomorphism on homotopy groups induced by the inclusion map i: X-0 --> X-C and obtain several results using rational homotopy theory and other standard tools of homotopy theory.
Invariant manifolds and Grobman-Hartman theorem for equations with degenerate operator at the derivative
Karasözen, Bülent; Loginov, B (2003-01-01)
Analog of Grobman-Hartman theorem about stable and unstable manifolds solutions for differential equations in Banach spaces with degenerate Fredholm operator at the derivative are proved. In contrast to usual evolution equation here central manifold arises even in the case of spectrum absence on the imaginary axis. Jordan chains tools and implicit operator theorem are used. The obtained results allow to develop center manifold methods for computation of bifurcation solution asymptotics and their stability i...
Citation Formats
E. GarciaRio, D. Kupeli, and M. VazquezAbal, “On a problem of Osserman in Lorentzian geometry,” DIFFERENTIAL GEOMETRY AND ITS APPLICATIONS, pp. 85–100, 1997, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/66749.