We propose definitions of QAC^0, the quantum analog of the classical class AC^0 of constant-depth circuits with AND and OR gates of arbitrary fan-in, and QACC^0[q], where n-ary Mod-q gates are also allowed. We show that it is possible to make a `cat' state on n qubits in constant depth if and...

In many complex systems control situations, searching for solutions or alternatives is involved. Searching for solutions can be modeled by a search on a fitness landscape. Knowing the structure of the underlying landscape can help in explaining or predicting aspects of an actual seach on it, and...

In several species of ants, workers cooperate to retrieve large prey. Usually, one ant finds a prey item, tries to move it, and, when unsucessful for some time, recuits nestmates through direct contact or chemical marking. When a group of ants tries to move large prey, the ants change position...

An overlapping generations model of an exchange economy is considered, with individials having a fininte expected life-span. As the model is designed to be a fully playable game, conditions concerning birth, death, inheritance and bequests are fully specified.

Feynman and Margolus have shown that a closed, locally interacting quantum system is capable of performing deterministic computation. Feynman's system computes in a serial way. Margolus was able to extend Feynman's ideas to get quantum description of a cellular automaton, i.e. a model which...

We present a method for approximating a fitness landscapes as a superposition of "elementary" landscapes. Given a correlation function of the landscape in question we show that the relative amplitudes of contributions with P-ary interactions can be computed. We show an application to RNA free...

The polygamy threshold model states that if costs incurred are less than the benefits gained from a polygamous relationship in terms of male or habitat quality, then polygamy is favored and could evolve. Here we construct mathematical models and computer simulations to evaluate this hypothesis...

Urban centers present all over the world striking similarities which translate into universal laws describing their growth and morphology. In this paper, we study a simple 2-dimensional cellular automata model containing what we identfiy as essential ingredients in the dimographic change. the...

We show that voltage-sensitive macromolecules can, by the application of the right type of external voltage fluctuation, be focused with great probability into a desired kinetic substate. As an illustration we consider an eight-state model of the Shaker $K^+$ channel driven by dichotomous...

We look at price formation in a retail setting, that is, companies set prices, and consumers either accept prices or go someplace else. In contrast to most other models in this context, we use a two-dimensional spatial structure for information transmission, that is, consumers can only learn...