On Level persistence (Relevant level persistence numbers)
  The purpose of this note is to describe of a new set of numerical invariants, the relevant level persistence numbers, and make explicit their relationship with the four types of bar codes, a more familiar set of complete invariants for level persistence. The paper provides the opportunity to compare level persistence with the persistence introduced by Edelsbrunner- Letscher-Zomorodian called in this paper, as sub-level persistence. 
Dong Du
cs.CG