Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Real quadratic fields admitting universal lattices of rank7   In this paper, we will prove that if $d$ is sufficiently large square-free
positive rational integer, then there is no integral septenary universal
quadratic lattice over $\mathcal{O}_F$ where $F=\mathbb Q(\sqrt{d})$.

22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg