Published online by Cambridge University Press: 01 July 2016
Let  be a Poisson process of intensity one in the infinite plane ℝ2. We surround each point x of
 be a Poisson process of intensity one in the infinite plane ℝ2. We surround each point x of  by the open disc of radius r centred at x. Now let S n  be a fixed disc of area n, and let C r (S n ) be the set of discs which intersect S n . Write E r  k  for the event that C r (S n ) is a k-cover of S n , and F r  k  for the event that C r (S n ) may be partitioned into k disjoint single covers of S n . We prove that P(E r  k  ∖ F r  k ) ≤ c k  / logn, and that this result is best possible. We also give improved estimates for P(E r  k ). Finally, we study the obstructions to k-partitionability in more detail. As part of this study, we prove a classification theorem for (deterministic) covers of ℝ2 with half-planes that cannot be partitioned into two single covers.
 by the open disc of radius r centred at x. Now let S n  be a fixed disc of area n, and let C r (S n ) be the set of discs which intersect S n . Write E r  k  for the event that C r (S n ) is a k-cover of S n , and F r  k  for the event that C r (S n ) may be partitioned into k disjoint single covers of S n . We prove that P(E r  k  ∖ F r  k ) ≤ c k  / logn, and that this result is best possible. We also give improved estimates for P(E r  k ). Finally, we study the obstructions to k-partitionability in more detail. As part of this study, we prove a classification theorem for (deterministic) covers of ℝ2 with half-planes that cannot be partitioned into two single covers.
Supported by NSF grant CCF-0728928.
Supported by ARO grant W911NF-06-1-0076, and NSF grants CNS-0721983, CCF-0728928, and DMS-0906634.