Controlling tax evasion fluctuations
  We incorporate the behaviour of tax evasion into the standard two-dimensional Ising model and augment it by providing policy-makers with the opportunity to curb tax evasion via an appropriate enforcement mechanism. We discuss different network structures in which tax evasion may vary greatly over time if no measures of control are taken. Furthermore, we show that even minimal enforcement levels may help to alleviate this problem substantially. 
Frank Westerhoff, Welington Lima, Georg Zaklan