Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the investigations of Ivan Prodanov in the theory of abstract spectra   The results of Iv. Prodanov on abstract spectra and separative algebras were
announced in the journal "Trudy Mat. Inst. Steklova", 154, 1983, 200--208, but
their proofs were never written by him in the form of a manuscript, preprint or
paper. Since the untimely death of Ivan Prodanov withheld him from preparing
the full version of this paper and since, in our opinion, it contains
interesting and important results, we undertook the task of writing a full
version of it and thus making the results from it known to the mathematical
community. So, the aim of this paper is to supply with proofs the results of
Ivan Prodanov announced in the cited above paper, but we added also a small
amount of new results. The full responsibility for the correctness of the
proofs of the assertions presented below in this work is taken by us; just for
this reason our names appear as authors of the present paper.

13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph