Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Algebra for generalised quantum observables   Generalised observables (POM observables) are necessary for representing all
possible measurements on a quantum system. Useful algebraic operations such as
addition and multiplication are defined for these observables, recovering many
advantages of the more restrictive Hermitian operator formalism. Examples
include new uncertainty relations and metrics, and optical phase applications.

35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg