Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New binary self-dual codes via a generalization of the four circulant
  construction   In this work, we generalize the four circulant construction for self-dual
codes. By applying the constructions over the alphabets F_2, F_2 + uF_2,
F_4+uF_4, we were able to obtain extremal binary self-dual codes of lengths 40,
64 including new extremal binary self-dual codes of length 68. More precisely,
43 new extremal binary self-dual codes of length 68, with rare new parameters
have been constructed.

29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc