Mathematical modelling of wealth distribution How is the mathematics in modelling of wealth distribution developed? What kind of mathematics is used and how accurately is it able to model this economic phenomena? An example is the Bouchard Mezard model. 
If anybody is familiar with the article "Degree and wealth distribution in a network induces by wealth" by G.Lee and G.Kim some explanation to the processes behind the equations would be very much appreciated.
Any kind of information, sources or input of any kind is very much appreciated. Thank you.
 A: My favourite introduction to the modelling of wealth starts from physics rather than mathematics: Statistical mechanics of money, wealth, and income by Yakovenko and Rosser. Their point is that for the majority of the population the dynamics of money is well described by equilibrium statistical mechanics.

By analogy with the Boltzmann-Gibbs distribution of energy in physics,
  it is shown that the probability distribution of money is exponential
  for certain classes of models with interacting economic agents.
  Money plays the role of energy, to the extent that it is a conserved quantity. Conservation of money in a closed system naturally leads to an exponential distribution of wealth, analogous to the Boltzmann-Gibbs distribution. This applies to the majority of the population. The power law Pareto distribution applies to the tail of the distribution, containing the most wealthy individuals. These results suggest that the presence of a power-law tail is a nonequilibrium effect that requires constant growth or inflation of the economy, but disappears for a closed system with conservation laws.


“Money, it’s a gas.” Pink Floyd, Dark Side of the Moon
