We study the frequency distribution of family names. From a common data base, we count the number of people who share the same family name. This is the size of the family. We find that (i) the total number of different family names in a society scales as a power law of the population, (ii) the...

We extend the Eden model to the binary system of two kinds of sites with different noise reduction parameters n and m(⩾n). The new model called binary Eden model connects the original Eden model (n=m=1) to the percolation model (n=1 and m=∞). From our numerical simulation on a square lattice...

One plus one dimensional growth of an Eden model with acceleration sites is investigated by simulations, where the acceleration sites which are distributed at random before the process starts become immediately Eden cells if the surface of Eden cluster touches them. The critical concentration of...