The neighbor-scattering number can be computed in polynomial time for   interval graphs
  Neighbor-scattering number is a useful measure for graph vulnerability. For some special kinds of graphs, explicit formulas are given for this number. However, for general graphs it is shown that to compute this number is NP-complete. In this paper, we prove that for interval graphs this number can be computed in polynomial time. 
Fengwei Li, Xueliang Li