Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Hierarchy of Voids   We present a model for the distribution of void sizes and its evolution
within the context of hierarchical scenarios of gravitational structure
formation. For a proper description of the hierarchical buildup of the system
of voids in the matter distribution, not only the "void-in-void" problem should
be taken into account, but also that of the "void-in-cloud" issue. Within the
context of the excursion set formulation of an evolving void hierarchy is one
involving a "two-barrier" excursion problem, unlike the "one-barrier" problem
for the dark halo evolution. This leads to voids having a peaked size
distribution at any cosmic epoch, centered on a characteristic void size that
evolves self-similarly in time, this in distinct contrast to the distribution
of virialized halo masses which do not have a small-scale cut-off.

16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol