4,888 research outputs found

### Univariate approximations in the infinite occupancy scheme

The paper concerns the classical occupancy scheme with infinitely many boxes.
We establish approximations to the distributions of the number of occupied
boxes, and of the number of boxes containing exactly r balls, within the family
of translated Poisson distributions. These are shown to be of ideal asymptotic
order, with respect both to total variation distance and to the approximation
of point probabilities. The proof is probabilistic, making use of a translated
Poisson approximation theorem of R\"ollin (2005).Comment: 20 page

### A central limit theorem for the gossip process

The Aldous gossip process represents the dissemination of information in
geographical space as a process of locally deterministic spread, augmented by
random long range transmissions. Starting from a single initially informed
individual, the proportion of individuals informed follows an almost
deterministic path, but for a random time shift, caused by the stochastic
behaviour in the very early stages of development. In this paper, it is shown
that, even with the extra information available after a substantial development
time, this broad description remains accurate to first order. However, the
precision of the prediction is now much greater, and the random time shift is
shown to have an approximately normal distribution, with mean and variance that
can be computed from the current state of the process

### Central limit theorems in the configuration model

We prove a general normal approximation theorem for local graph statistics in
the configuration model, together with an explicit bound on the error in the
approximation with respect to the Wasserstein metric. Such statistics take the
form $T := \sum_{v \in V} H_v$, where $V$ is the vertex set, and $H_v$ depends
on a neighbourhood in the graph around $v$ of size at most $\ell$. The error
bound is expressed in terms of $\ell$, $|V|$, an almost sure bound on $H_v$,
the maximum vertex degree $d_{\max}$ and the variance of $T$. Under suitable
assumptions on the convergence of the empirical degree distributions to a
limiting distribution, we deduce that the size of the giant component in the
configuration model has asymptotically Gaussian fluctuations.Comment: minor change

### Asymptotic behaviour of gossip processes and small world networks

Both small world models of random networks with occasional long range
connections and gossip processes with occasional long range transmission of
information have similar characteristic behaviour. The long range elements
appreciably reduce the effective distances, measured in space or in time,
between pairs of typical points. In this paper, we show that their common
behaviour can be interpreted as a product of the locally branching nature of
the models. In particular, it is shown that both typical distances between
points and the proportion of space that can be reached within a given distance
or time can be approximated by formulae involving the limit random variable of
the branching process.Comment: 30 page

### Assessing molecular variability in cancer genomes

The dynamics of tumour evolution are not well understood. In this paper we
provide a statistical framework for evaluating the molecular variation observed
in different parts of a colorectal tumour. A multi-sample version of the Ewens
Sampling Formula forms the basis for our modelling of the data, and we provide
a simulation procedure for use in obtaining reference distributions for the
statistics of interest. We also describe the large-sample asymptotics of the
joint distributions of the variation observed in different parts of the tumour.
While actual data should be evaluated with reference to the simulation
procedure, the asymptotics serve to provide theoretical guidelines, for
instance with reference to the choice of possible statistics.Comment: 22 pages, 1 figure. Chapter 4 of "Probability and Mathematical
Genetics: Papers in Honour of Sir John Kingman" (Editors N.H. Bingham and
C.M. Goldie), Cambridge University Press, 201

### A functional combinatorial central limit theorem

The paper establishes a functional version of the Hoeffding combinatorial
central limit theorem. First, a pre-limiting Gaussian process approximation is
defined, and is shown to be at a distance of the order of the Lyapounov ratio
from the original random process. Distance is measured by comparison of
expectations of smooth functionals of the processes, and the argument is by way
of Stein's method. The pre-limiting process is then shown, under weak
conditions, to converge to a Gaussian limit process. The theorem is used to
describe the shape of random permutation tableaux.Comment: 23 page

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