Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A characterization of the number of subsequences obtained via the
  deletion channel   Motivated by the study of deletion channels, this work presents improved
bounds on the number of subsequences obtained from a binary sting X of length n
under t deletions. It is known that the number of subsequences in this setting
strongly depends on the number of runs in the string X; where a run is a
maximal sequence of the same character. Our improved bounds are obtained by a
structural analysis of the family of r-run strings X, an analysis in which we
identify the extremal strings with respect to the number of subsequences.
Specifically, for every r, we present r-run strings with the minimum
(respectively maximum) number of subsequences under any t deletions; and
perform an exact analysis of the number of subsequences of these extremal
strings.

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The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg