Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Almost Designs and Their Links with Balanced Incomplete Block Designs   Almost designs ($t$-adesigns) were proposed and discussed by Ding as a
certain generalization of combinatorial designs related to almost difference
sets. Unlike $t$-designs, it is not clear whether $t$-adesigns need also be
$(t-1)$-designs or $(t-1)$-adesigns. In this paper we discuss a particular
class of 3-adesigns, i.e., 3-adesigns coming from certain strongly regular
graphs and tournaments, and find that these are also $2$-designs. We construct
several classes of these, and discuss some of the restrictions on the
parameters of such a class. We also construct several new classes of
2-adesigns, and discuss some of their properties as well.

28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin