Coevolution Models with Dynamically Changing Mutation Partners

다국어 초록 (Multilingual Abstract)

We study a modified Bak-Sneppen model with dynamically changing mutation partners. Each
site on a one-dimensional lattice has a fitness value fi. In a unit update, the site which has the
minimum fitness value fmin is selected. Then the selected site and the sites within a distance l from
the selected site are updated to new random values. The distance l is stochastically chosen from a
power-law distribution P(l) l.μ. We measure the critical fitness and the avalanche distribution
in stationary states. For μ < 2, the critical fitness value satisfies the power law fc(N) N.. For
μ > 2, fc is finite and approaches the one-dimensional value as μ ! 1. Logarithmic behavior is
shown at μ = 2. The avalanche distribution satisfies a normal power law P(s) s. . For μ 2,
the exponent ’s have the same value 1.66 within the error bar. However, with increasing μ the
avalanche exponent is continuously varying for μ > 2 and approaches the exponent of the onedimensional
BS model. We also study the dynamical network structures developed by the present
coevolution model.?劑맰