  We show that the heterogeneity index, which was proposed by Hu and Wang
(Physica A 2008 387 3769), can be used to describe the disparity of the
cooperation sharing or competition gain distributions that is very important
for the cooperation/competition system dynamic understanding. An analytical
relation between the distribution parameters and the heterogeneity index is
derived, which is in a good agreement with the empirical results. Our
theoretical and empirical analyses also show that the relation between the
distribution parameters can be analytically derived from so-called Zhang-Chang
model (Physica A 2006 360 599 and 2007 383 687). This strongly recommends a
possibility to create a general dynamic cooperation/competition model based on
Zhang-Chang model.
