Half-lightlike altmanifoldlar

In the first chapter of this thesis that consists of three chapters, the goal of the work and its importance in the literature are emphasized.In the second chapter, the lightlike submanifolds and lightlike hypersurfaces of a Semi-Riemann manifolds are defined and the main definitions and theorems which are necessary for our study are given.In the third chapter, the definition of half-lightlike submanifolds is given. The Gauss-Weingarten equations and Riemann curvature tensors of a half-lightlike submanifold are calculated. Basic definitions and theorems for total umbilical, screen conformal and irrotational screen homothetic half-lightlike submanifolds are given.