We consider a Boolean model Z driven by a Poisson particle process η on a metric space Y. We study the random variable ρ(Z), where ρ is a (deterministic) measure on Y. Due to the interaction of overlapping particles, the distribution of ρ(Z) cannot be described explicitly. In this note we derive concentration inequalities for ρ(Z). To this end we first prove two concentration inequalities for functions of a Poisson process on a general phase space.2000 Mathematics Subject Classification. 60D05, 60G55.1 reason for the absence of such formulae is the interaction between the particles from η caused by overlapping. One way out are moment formulae and central limit theorems; see e.g. [10] and [13, Chapter 22]. In this paper we will prove concentration inequalities of the formwhere the function : [0, ∞) → [0, ∞] is determined by Λ and ρ. In the stationary Euclidean case such inequalities were first proved in [7]. Our bounds improve these results. Moreover, we generalize the setting of [7] in several ways. First, we study the Boolean model on a metric space Y and not only on R d . Second, we will allow that compact subsets of Y are intersected by infinitely many Poisson particles. Hence, in general, the random set Z is not closed and its boundary might have fractal properties. Roughly speaking, this means that we can allow for a σ-finite distribution of the typical grain. Closely related models of this type were introduced in [21], a seminal paper on fractal percolation, that was almost completely ignored in the later literature. Third, we consider general measures and not only the volume. Finally, our method allows to treat also Lipschitz functions of these measures.Similarly as in [8,9] our approach is based on a covariance identity for square integrable Poisson functionals. In fact we first prove a concentration inequality for functions of a Poisson process on a general phase space. Using the log-Sobolev inequality, related concentration inequalities were derived in [2,1,19].
Concentration of Poisson functionalsLet (X, X) be a measurable space and let Λ be a σ-finite measure on X. Let η be a Poisson process on X with intensity measure Λ, defined over a probability space (Ω, A, P); see [13]. In particular, η is a point process, that is a measurable mapping from Ω to the space N = N(X) of all σ-finite measures with values inN 0 := {∞, 0, 1, 2, . . .}, where N is equipped with the smallest σ-field N such that µ → µ(B) is measurable for all B ∈ X. The distribution of η is denoted by Π Λ := P(η ∈ ·). Since we are only interested in distributional properties of η, Corollary 6.5 in [13] shows that it is no restriction of generality to assume that η is proper. This means that there exist random elements X 1 , X 2 , . . . in X and anN 0 -valued random variable κ such that almost surely η = κ n=1 δ X n . Let 0 ≤ t ≤ 1 and Y 1 , Y 2 , . . . be a sequence of independent random variables with distribution (1 − t)δ 0 + tδ 1 , independent of η. Define η t := κ n=1 Y n δ X n as the t-thinning of η. Then η t and η − η t are independ...