Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A novel conductivity mechanism of highly disordered carbon systems based
  on an investigation of graph zeta function   In the previous report [Phys. Rev. B {\bf{62}} 13812 (2000)], by proposing
the mechanism under which electric conductivity is caused by the activational
hopping conduction with the Wigner surmise of the level statistics, the
temperature-dependent of electronic conductivity of a highly disordered carbon
system was evaluated including apparent metal-insulator transition. Since the
system consists of small pieces of graphite, it was assumed that the reason why
the level statistics appears is due to the behavior of the quantum chaos in
each granular graphite. In this article, we revise the assumption and show
another origin of the Wigner surmise, which is more natural for the carbon
system based on a recent investigation of graph zeta function in graph theory.

17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys