  In neutrinoless double beta (0{\nu}{\beta}{\beta}) decay experiments, the
diversity of topological signatures of different particles provides an
important tool to distinguish double beta events from background events and
reduce background rates. Aiming at suppressing the single-electron backgrounds
which are most challenging, several groups have established Monte Carlo
simulation packages to study the topological characteristics of single-electron
events and 0{\nu}{\beta}{\beta} events and develop methods to differentiate
them. In this paper, applying the knowledge of graph theory, a new topological
signature called REF track (Refined Energy-Filtered track) is proposed and
proven to be an accurate approximation of the real particle trajectory. Based
on the analysis of the energy depositions along the REF track of
single-electron events and 0{\nu}{\beta}{\beta} events, the REF energy
deposition models for both events are proposed to indicate the significant
differences between them. With these differences, this paper presents a new
discrimination method, which, in the Monte Carlo simulation, achieved a
single-electron rejection factor of 93.8+-0.3 (stat.)% as well as a
0{\nu}{\beta}{\beta} efficiency of 85.6+-0.4 (stat.)% with optimized parameters
in CdZnTe.
