A Particular Bit of Universality: Scaling Limits of Some Dependent Percolation Models

We study families of dependent site percolation models on the triangular lattice and hexagonal lattice that arise by applying certain cellular automata to independent percolation configurations. We analyze the scaling limit of such models and show that the distance between macroscopic portions of cluster boundaries of any two percolation models within one of our families goes to zero almost surely in the scaling limit. It follows that each of these cellular automaton generated dependent percolation models has the same scaling limit (in the sense of Aizenman-Burchard [3]) as independent site percolation on .The work was conducted while this author was at Department of Physics, New York University, New York, NY 10003, USA. Research partially supported by the U.S. NSF under grants DMS-98-02310 and DMS-01-02587.Research partially supported by the U.S. NSF under grants DMS-98-03267 and DMS-01-04278.Research partially supported by FAPERJ grant E-26/151.905/2000 and CNPq.     

Quenched invariance principles for walks on clusters of percolation or among random conductances

In this work we principally study random walk on the supercritical infinite cluster for bond percolation on ^d. We prove a quenched functional central limit theorem for the walk when d4. We also prove a similar result for random walk among i.i.d. random conductances along nearest neighbor edges of ^d, when d1.V. Sidoravicius would like to thank the FIM for financial support and hospitality during his multiple visits to ETH. His research was also partially supported by FAPERJ and CNPq.     

Percolation in Media with Columnar Disorder

We study a generalization of site percolation on a simple cubic lattice, where not only single sites are removed randomly, but also entire parallel columns of sites. We show that typical clusters near the percolation transition are very anisotropic, with different scaling exponents for the sizes parallel and perpendicular to the columns. Below the critical point there is a Griffiths phase where cluster size distributions and spanning probabilities in the direction parallel to the columns have power-law tails with continuously varying non-universal powers. This region is very similar to the Griffiths phase in subcritical directed percolation with frozen disorder in the preferred direction, and the proof follows essentially the same arguments as in that case. But in contrast to directed percolation in disordered media, the number of active (“growth”) sites in a growing cluster at criticality shows a power law, while the probability of a cluster to continue to grow shows logarithmic behavior.     

Stability of the Greedy Algorithm on the Circle

We consider a single‐server system with service stations in each point of the circle. Customers arrive after exponential times at uniformly distributed locations. The server moves at finite speed and adopts a greedy routing mechanism. It was conjectured by Coffman and Gilbert in 1987 that the service rate exceeding the arrival rate is a sufficient condition for the system to be positive recurrent, for any value of the speed. In this paper we show that the conjecture holds true.© 2017 Wiley Periodicals, Inc.     

Absence of Infinite Cluster for Critical Bernoulli Percolation on Slabs

We prove that for Bernoulli percolation on a graph , there is no infinite cluster at criticality, almost surely. The proof extends to finite‐range Bernoulli percolation models on ?² that are invariant under ‐rotation and reflection.© 2016 Wiley Periodicals, Inc.     

Gaussian Stationary Processes: Adaptive Wavelet Decompositions,Discrete Approximations,and Their Convergence

We establish particular wavelet-based decompositions of Gaussian stationary processes in continuous time. These decompositions have a multiscale structure, independent Gaussian random variables in high-frequency terms, and the random coefficients of low-frequency terms approximating the Gaussian stationary process itself. They can also be viewed as extensions of the earlier wavelet-based decompositions of Zhang and Walter (IEEE Trans. Signal Process. 42(7):1737–1745, [1994]) for stationary processes, and Meyer et al. (J. Fourier Anal. Appl. 5(5):465–494, [1999]) for fractional Brownian motion. Several examples of Gaussian random processes are considered such as the processes with rational spectral densities. An application to simulation is presented where an associated Fast Wavelet Transform-like algorithm plays a key role. The second author was supported in part by the NSF grant DMS-0505628.     

Absence of site percolation at criticality in

In this note we consider site percolation on a two dimensional sandwich of thickness two, the graph . We prove that there is no percolation at the critical point. The same arguments are valid for a sandwich of thickness three with periodic boundary conditions. It remains an open problem to extend this result to other sandwiches. “Note added in proof: This extension has recently been accomplished in arXiv 1401.7130.” © 2014 Wiley Periodicals, Inc. Random Struct. Alg., 47, 328–340, 2015