On the Robustness of NK-Kauffman Networks Against Changes in their Connections and Boolean Functions
arXiv:0903.4161 · doi:10.1063/1.3116166
Abstract
NK-Kauffman networks {\cal L}^N_K are a subset of the Boolean functions on N Boolean variables to themselves, Λ_N = {ξ: \IZ_2^N \to \IZ_2^N}. To each NK-Kauffman network it is possible to assign a unique Boolean function on N variables through the function Ψ: {\cal L}^N_K \to Λ_N. The probability {\cal P}_K that Ψ(f) = Ψ(f'), when f' is obtained through f by a change of one of its K-Boolean functions (b_K: \IZ_2^K \to \IZ_2), and/or connections; is calculated. The leading term of the asymptotic expansion of {\cal P}_K, for N \gg 1, turns out to depend on: the probability to extract the tautology and contradiction Boolean functions, and in the average value of the distribution of probability of the Boolean functions; the other terms decay as {\cal O} (1 / N). In order to accomplish this, a classification of the Boolean functions in terms of what I have called their irreducible degree of connectivity is established. The mathematical findings are discussed in the biological context where, Ψis used to model the genotype-phenotype map.
17 pages, 1 figure, Accepted in Journal of Mathematical Physics