Closing probabilities in the Kauffman model: an annealed computation

We define a probabilistic scheme to compute the distributions of periods, transients and weigths of attraction basins in Kauffman networks. These quantities are obtained in the framework of the annealed approximation, first introduced by Derrida and Pomeau. Numerical results are in good agreement with the computed values of the exponents of average periods, but show also some interesting features which can not be explained whithin the annealed approximation.Comment: latex, 36 pages, figures added in uufiles format,error in epsffile nam

Kinetics of Coalescence, Annihilation, and the q-State Potts Model in One Dimension

The kinetics of the q-state Potts model in the zero temperature limit in one dimension is analyzed exactly through a generalization of the method of empty intervals, previously used for the analysis of diffusion-limited coalescence, A+A->A. In this new approach, the q-state Potts model, coalescence, and annihilation (A+A->0) all satisfy the same diffusion equation, and differ only in the imposed initial condition.Comment: 4 pages, RevTeX, submitted to Phys. Lett.

Damage spreading in the 'sandpile' model of SOC

We have studied the damage spreading (defined in the text) in the 'sandpile' model of self organised criticality. We have studied the variations of the critical time (defined in the text) and the total number of sites damaged at critical time as a function of system size. Both shows the power law variation.Comment: 5 pages Late

Relevant elments, Magnetization and Dynamical Properties in Kauffman Networks: a Numerical Study

This is the first of two papers about the structure of Kauffman networks. In this paper we define the relevant elements of random networks of automata, following previous work by Flyvbjerg and Flyvbjerg and Kjaer, and we study numerically their probability distribution in the chaotic phase and on the critical line of the model. A simple approximate argument predicts that their number scales as sqrt(N) on the critical line, while it is linear with N in the chaotic phase and independent of system size in the frozen phase. This argument is confirmed by numerical results. The study of the relevant elements gives useful information about the properties of the attractors in critical networks, where the pictures coming from either approximate computation methods or from simulations are not very clear.Comment: 22 pages, Latex, 8 figures, submitted to Physica

"As Nobody I was Sovereign": reading Derrida reading Blanchot

In Session 7 (26 February 2003) of The Beast and the Sovereign, Volume II, Jacques Derrida engages again with Maurice Blanchot, two days after the latter’s cremation. This intervention also appears as a post-face to Derrida’s 2003 edition of Parages, his collection of essays devoted to the work of Blanchot. In this article, I examine Derrida’s affinity to the work of Blanchot, as the one whose work ‘stood watch over and around what matters to me, for a long time behind me and forever still before me’ [The Beast and the Sovereign, Volume II, p. 176]. In doing so I look at the manner in which Derrida engaged with Blanchot in his work and how in examining this engagement another reading of sovereignty emerges, one which is not tethered to liberal models of sovereign will but one which eludes biopolitical ordering and may be seen as a form of disappearance. Through a reading of Derrida’s readings of Blanchot’s The Madness of the Day I emphasize the link of this alternative sovereignty to both writing and literature in order to demonstrate how a more radical thinking of sovereignty can be discovered in Derrida’s thought

Hierarchic trees with branching number close to one: noiseless KPZ equation with additional linear term for imitation of 2-d and 3-d phase transitions.

An imitation of 2d field theory is formulated by means of a model on the hierarhic tree (with branching number close to one) with the same potential and the free correlators identical to 2d correlators ones. Such a model carries on some features of the original model for certain scale invariant theories. For the case of 2d conformal models it is possible to derive exact results. The renormalization group equation for the free energy is noiseless KPZ equation with additional linear term.Comment: latex, 5 page

Two-way traffic flow: exactly solvable model of traffic jam

We study completely asymmetric 2-channel exclusion processes in 1 dimension. It describes a two-way traffic flow with cars moving in opposite directions. The interchannel interaction makes cars slow down in the vicinity of approaching cars in other lane. Particularly, we consider in detail the system with a finite density of cars on one lane and a single car on the other one. When the interchannel interaction reaches a critical value, traffic jam occurs, which turns out to be of first order phase transition. We derive exact expressions for the average velocities, the current, the density profile and the $k$- point density correlation functions. We also obtain the exact probability of two cars in one lane being distance $R$ apart, provided there is a finite density of cars on the other lane, and show the two cars form a weakly bound state in the jammed phase.Comment: 17 pages, Latex, ioplppt.sty, 11 ps figure

Phase Transition in NK-Kauffman Networks and its Correction for Boolean Irreducibility

In a series of articles published in 1986 Derrida, and his colleagues studied two mean field treatments (the quenched and the annealed) for \textit{NK}-Kauffman Networks. Their main results lead to a phase transition curve $K_c \, 2 \, p_c \left( 1 - p_c \right) = 1$ ($0 < p_c < 1$) for the critical average connectivity $K_c$ in terms of the bias $p_c$ of extracting a "$1$" for the output of the automata. Values of $K$ bigger than $K_c$ correspond to the so-called chaotic phase; while $K < K_c$, to an ordered phase. In~[F. Zertuche, {\it On the robustness of NK-Kauffman networks against changes in their connections and Boolean functions}. J.~Math.~Phys. {\bf 50} (2009) 043513], a new classification for the Boolean functions, called {\it Boolean irreducibility} permitted the study of new phenomena of \textit{NK}-Kauffman Networks. In the present work we study, once again the mean field treatment for \textit{NK}-Kauffman Networks, correcting it for {\it Boolean irreducibility}. A shifted phase transition curve is found. In particular, for $p_c = 1 / 2$ the predicted value $K_c = 2$ by Derrida {\it et al.} changes to $K_c = 2.62140224613 \dots$ We support our results with numerical simulations.Comment: 23 pages, 7 Figures on request. Published in Physica D: Nonlinear Phenomena: Vol.275 (2014) 35-4

Multiple Shocks in a Driven Diffusive System with Two Species of Particles

A one-dimensional driven diffusive system with two types of particles and nearest neighbors interactions has been considered on a finite lattice with open boundaries. The particles can enter and leave the system from both ends of the lattice and there is also a probability for converting the particle type at the boundaries. We will show that on a special manifold in the parameters space multiple shocks evolve in the system for both species of particles which perform continuous time random walks on the lattice.Comment: 11 pages, 1 figure, accepted for publication in Physica

Persistence exponent in a superantiferromagnetic quenching

We measure the persistence exponent in a phase separating two-dimensional spin system with non-conserved dynamics quenched in a region with four coexisting stripe phases. The system is an Ising model with nearest neighbor, next-to-the-nearest neighbor and plaquette interactions. Due the particular nature of the ground states, the order parameter is defined in terms of blocks of spins. Our estimate of the persistence exponent, $\theta=0.42$, differs from those of the two-dimensional Ising and four state Potts models. Our procedure allows the study of persistence properties also at finite temperature $T$: our results are compatible with the hypothesis that $\theta$ does not depend on $T$ below the critical point.Comment: LaTeX file with postscript figure