Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Black hole formation from colliding bubbles   Some indication of conditions that are necessary for the formation of black
holes from the collision of bubbles during a supercooled phase transition in
the the early universe are explored. Two colliding bubbles can never form a
black hole. Three colliding bubbles can refocus the energy in their walls to
the extent that it becomes infinite.

29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol