Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Time of Events in Quantum Theory   We enhance elementary quantum mechanics with three simple postulates that
enable us to define time observable. We discuss shortly justification of the
new postulates and illustrate the concept with the detailed analysis of a delta
function counter.

10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin