Bit-strings and other modifications of Viviane model for language   competition
  The language competition model of Viviane de Oliveira et al is modified by associating with each language a string of 32 bits. Whenever a language changes in this Viviane model, also one randomly selected bit is flipped. If then only languages with different bit-strings are counted as different, the resulting size distribution of languages agrees with the empirically observed slightly asymmetric log-normal distribution. Several other modifications were also tried but either had more free parameters or agreed less well with reality. 
P.M.C. de Oliveira, D. Stauffer, F.W.S. Lima, A.O. Sousa, C. Schulze   and S. Moss de Oliveira