Change in Order of Phase Transitions on Fractal Lattices
  We re-examine a population model which exhibits a continuous absorbing phase transition which belongs to directed percolation in 1+1 dimensions and a first order transition in 2+1 dimensions and above. Studying the model on fractal lattices, we examine at what fractal dimension 1<d_f<2, the change in order occurs. As well as commenting on the order of the transitions, we produce estimates for the critical points and, for continuous transitions, some critical exponents. 
Alastair L Windus and Henrik Jeldtoft Jensen