We characterize the distributions of short cycles in a large metabolic network previously shown to have small world characteristics and a power law degree distribution. Compared with three networks of the same connectivity, the metabolic network has a particularly large number of triangles and a...

A model for haploid asexual inheritance of social and individual learning is proposed. Animals of one genotype, individual learners (IL), behave optimally for the current environment and, except for a fixed cost due to learning errors, have the optimal fitness in that environment. Animals of the...

Technological change at the firm level has commonly been modeled as random sampling from a fixed distribution o f possibilities. Such models, however, typically ignore empirically important aspects of the firm's search process, notably the observation that the present state of the firm guides...

The time evolution of a simple model for crossover is discussed. A variant of this model with an improved exploration behavior in phase space is derived as a subset of standard one- and multi-point crossover operations. This model is solved analytically in the flat fitness case. Numerical...

In this paper we review some previously published experimental results in which a simple hill-climbing algorithm---Random Mutation Hill-Climbing (RMHC)---significantly outperforms a genetic algorithm on a simple ``Royal Road'' function. We present an analysis of RMHC followed by an analysis of...

The field of artificial intelligence (AI) has as its goal the development of machines that can perceive, reason, communicate, and act in complex environments much like humans can, or possibly even better than humans can. Even though the field has produced some practically useful machines with...

Basic research is no longer confined just to ivory towers and is no longer confined to just a few interested people. The money which is spent for basic research is tremendous. The annual budget of the German National Science Foundation (DFG) is larger than 1.5 Billion DM (1 Billion US Dollar)....

We propose some simple models of the growth of social networks, based on three general principles: (1) meetings take place between pairs of individuals at a rate which is high if a pair has one or more mutual friends and low otherwise; (2) acquaintances between pairs of individuals who rarely...

RNA free energy landscapes are analyzed by means of "time-series" that are obtained from random walks restricted to excursion sets. The power spectra, the scaling of the jump size distribution, and the scaling of the curve length measured with different yard stick lengths are used to describe...

High-dimensional integrals are usually solved with Monte Carlo algorithms although theory suggests that low-discrepancy algorithms are sometimes superior. We report on numerical testing which compares low-discrepancy and Monte Carlo algorithms on the evaluation of financial derivatives. The...