characterization of osculating and rectifying curves in semi-euclidean space of index 2

Osculating and rectifying curves in euclidean space andminkowski space were investigated in several articles. in this paper the con-cept of osculating and rectifying null and partially null curves are generalizedin four dimensional semi-euclidean space of index two and the coecients oftheir position vector in each case by using of frenet equations, are given. par-tially null curves with constant second and third curvature are classied andit is shown that partially null curves with zero second curvature are planer. inaddition, a characterization for rectifying null curves is given and it is shownthat any null rectifying curve with constant second and third curvature isspherical.