For an edge-weighted graph
G with
n vertices and
m edges, the minimum
k-way cut problem is to find a partition of the vertex set into
k non-empty subsets so that the weight sum of edges between different subsets is minimized. For this problem with
k = 5 and 6, we present a deterministic algorithm that runs in
$
O\left( {n^{k - 2} \left( {nF\left( {n,m} \right) + C_2 \left( {n,m} \right) + n^2 } \right)} \right) = O\left( {mn^k \log \left( {n^2 /m} \right)} \right)
$
O\left( {n^{k - 2} \left( {nF\left( {n,m} \right) + C_2 \left( {n,m} \right) + n^2 } \right)} \right) = O\left( {mn^k \log \left( {n^2 /m} \right)} \right)
time, where
F(
n,
m) and
C
2
(
n,
m) denote respectively the time bounds required to solve the maximum flow problem and the minimum 2-way cut problem in
G. The bounds
$
\tilde O\left( {mn^5 } \right)
$
\tilde O\left( {mn^5 } \right)
for
k = 5 and
$
\tilde O\left( {mn^6 } \right)
$
\tilde O\left( {mn^6 } \right)
for
k = 6 improve the previous best randomized bounds
$
\tilde O\left( {n^8 } \right)
$
\tilde O\left( {n^8 } \right)
and
$
\tilde O\left( {n^{10} } \right)
$
\tilde O\left( {n^{10} } \right)
, respectively.
This research was partially supported by the Scientific Grant-in-Aid from Ministry of Education, Science, Sports and Culture
of Japan, and the subsidy from the Inamori Foundation.