2,157 research outputs found
Probabilistic cellular automata with conserved quantities
We demonstrate that the concept of a conservation law can be naturally
extended from deterministic to probabilistic cellular automata (PCA) rules. The
local function for conservative PCA must satisfy conditions analogous to
conservation conditions for deterministic cellular automata. Conservation
condition for PCA can also be written in the form of a current conservation
law. For deterministic nearest-neighbour CA the current can be computed
exactly. Local structure approximation can partially predict the equilibrium
current for non-deterministic cases. For linear segments of the fundamental
diagram it actually produces exact results.Comment: 17 pages, 2 figure
Enhancing Approximations for Regular Reachability Analysis
This paper introduces two mechanisms for computing over-approximations of
sets of reachable states, with the aim of ensuring termination of state-space
exploration. The first mechanism consists in over-approximating the automata
representing reachable sets by merging some of their states with respect to
simple syntactic criteria, or a combination of such criteria. The second
approximation mechanism consists in manipulating an auxiliary automaton when
applying a transducer representing the transition relation to an automaton
encoding the initial states. In addition, for the second mechanism we propose a
new approach to refine the approximations depending on a property of interest.
The proposals are evaluated on examples of mutual exclusion protocols
Towards Static Analysis of Functional Programs using Tree Automata Completion
This paper presents the first step of a wider research effort to apply tree
automata completion to the static analysis of functional programs. Tree
Automata Completion is a family of techniques for computing or approximating
the set of terms reachable by a rewriting relation. The completion algorithm we
focus on is parameterized by a set E of equations controlling the precision of
the approximation and influencing its termination. For completion to be used as
a static analysis, the first step is to guarantee its termination. In this
work, we thus give a sufficient condition on E and T(F) for completion
algorithm to always terminate. In the particular setting of functional
programs, this condition can be relaxed into a condition on E and T(C) (terms
built on the set of constructors) that is closer to what is done in the field
of static analysis, where abstractions are performed on data.Comment: Proceedings of WRLA'14. 201
The dynamical origin of the universality classes of spatiotemporal intermittency
Studies of the phase diagram of the coupled sine circle map lattice have
identified the presence of two distinct universality classes of spatiotemporal
intermittency viz. spatiotemporal intermittency of the directed percolation
class with a complete set of directed percolation exponents, and spatial
intermittency which does not belong to this class. We show that these two types
of behavior are special cases of a spreading regime where each site can infect
its neighbors permitting an initial disturbance to spread, and a non-spreading
regime where no infection is possible, with the two regimes being separated by
a line, the infection line. The coupled map lattice can be mapped on to an
equivalent cellular automaton which shows a transition from a probabilistic
cellular automaton to a deterministic cellular automaton at the infection line.
The origins of the spreading-non-spreading transition in the coupled map
lattice, as well as the probabilistic to deterministic transition in the
cellular automaton lie in a dynamical phenomenon, an attractor-widening crisis
at the infection line. Indications of unstable dimension variability are seen
in the neighborhood of the infection line. This may provide useful pointers to
the spreading behavior seen in other extended systems.Comment: 20 pages, 9 figure
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