Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Online Grammar Compression for Frequent Pattern Discovery   Various grammar compression algorithms have been proposed in the last decade.
A grammar compression is a restricted CFG deriving the string
deterministically. An efficient grammar compression develops a smaller CFG by
finding duplicated patterns and removing them. This process is just a frequent
pattern discovery by grammatical inference. While we can get any frequent
pattern in linear time using a preprocessed string, a huge working space is
required for longer patterns, and the whole string must be loaded into the
memory preliminarily. We propose an online algorithm approximating this problem
within a compressed space. The main contribution is an improvement of the
previously best known approximation ratio $\Omega(\frac{1}{\lg^2m})$ to
$\Omega(\frac{1}{\lg^*N\lg m})$ where $m$ is the length of an optimal pattern
in a string of length $N$ and $\lg^*$ is the iteration of the logarithm base
$2$. For a sufficiently large $N$, $\lg^*N$ is practically constant. The
experimental results show that our algorithm extracts nearly optimal patterns
and achieves a significant improvement in memory consumption compared to the
offline algorithm.

4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom