Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Some Recent Developments in the Decoherent Histories Approach to Quantum
  Theory   A brief introduction to the decoherent histories approach to quantum theory
is given, with emphasis on its role in the discussion of the emergence of
classicality from quantum theory. Some applications are discussed, including
quantum-classical couplings, the relationship of the histories approach to
quantum state diffusion, and the application of the histories approach to
situations involving time in a non-trivial way.

20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom