Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Abundance Distributions in Artificial Life and Stochastic Models: "Age
  and Area" revisited   Using an artificial system of self-replicating strings, we show a correlation
between the age of a genotype and its abundance that reflects a punctuated
rather than gradual picture of evolution, as suggested long ago by Willis. In
support of this correlation, we measure genotype abundance distributions and
find universal coefficients. Finally, we propose a simple stochastic model
which describes the dynamics of equilibrium periods and which correctly
predicts most of the observed distributions.

3
The categories of this paper are: physics
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th