Notes on Degenerate Curves in Pseudo-Euclidean Spaces of Index Two
  In this paper we deal with curves with degeneration degree two in pseudo-Euclidean spaces of index two. We characterize Bertrand curves. We show a correspondence between the evolute of a null curve and the involute of a certain spacelike curve in the $6-$dimensional pseudo-Euclidean space of index two. Also we characterize pseudo-spherical null curves in the $n-$dimensional pseudo-Euclidean space of index two in terms of the curvature functions. 
Mehmet G\"o\c{c}men, Sad{\i}k Kele\c{s}
math.DG