singularities in the theory of ordinary differential equations, dynamical systems, differential geometry, calculus of variations, and optimal control. Recently, the main theme of the work is singularities of geodesic flows in pseudo-Riemannian spaces with signature varying metrics. In particular, it was established that geodesic lines cannot pass through degenerate points of the metric in arbitrary tangential directions, but only in certain admissible directions. Generically, in 2-dimensional case, the number of admissible directions is finite and varies from one to three, but if the dimension is more than two, the number of admissible directions can be finite or infinite. A brief survey in the two-dimensional case is presented in: https://arxiv.org/pdf/1801.09815.pdf
Main publications:
A.O. Remizov, “Geodesics on 2-surfaces with pseudo-Riemannian metric: singularities of changes of signature”, Sb. Math., 200:3 (2009), 385–403
I.R. Shafarevich, A.O. Remizov, Linear Algebra and Geometry, Springer-Verlag Berlin and Heidelberg GmbH, 2013 (English)
R. Ghezzi, A.O. Remizov, “On a class of vector fields with discontinuities of divide-by-zero type and its applications to geodesics in singular metrics”, J. Dyn. Control Syst., 18:1 (2012), 135–158
A.O. Remizov, “On the local and global properties of geodesics in pseudo-Riemannian metrics”, Differential Geometry and its Applications, 39 (2015), 36–58
A.O. Remizov, F. Tari, “Singularities of the geodesic flow on surfaces with pseudo-Riemannian metrics”, Geometriae Dedicata, 185:1 (2016), 131–153
