An Intelligent Algorithm for the (1,2,2)-Generalized Knight’s Tour Problem
Sen Bai
1,2
1
Department of information Engineering, Chongqing
Communication Institute,
2
Chongqing Key Laboatory
of Emergency Communication
Chongqing, China
e-mail: baisencq@126.com, gabriel-zhu@163.com
Gui-Bin Zhu
1,2
, Jian Huang
1,2
1
Department of information Engineering, Chongqing
Communication Institute,
2
Chongqing Key Laboatory
of Emergency Communication
Chongqing, China
e-mail: Jianhuang1983@126.com
Abstract—In [Discrete Applied Mathematics 158(2010)1727-
1731], we proved that the 34 4qp×× (where 2q ≥ and
2p ≥
are integer) chessboard admits a closed (1,2,2)-generalized
knight’s tour (GKT). In this paper, we prove that a chessboard
of size
44
qp××
with
3L ≥ and 4L ≠ , 2q ≥ and
2p ≥
must contain a closed (1,2,2)-GKT. Next, an intelligent
algorithm based on the proved Lemma and Theorem is
proposed to find closed (1,2,2)-GKT on
44
qp××
chessboard.
The proposed algorithms for constructing structured (1,2,2)-
GKT Hamiltonian cycle on
44
qp××
chessboard can readily
be implemented in intelligence. Finally, the GKT Hamiltonian
cycle is applied to video encryption, and simulation
experimental results show that the GKT scrambling is suitable
for perceptual video encryption.
Keywords- Generalized knight’s tour; 3D chessboard;
Hamiltonian graph; Perceptual video encryption
I. INTRODUCTION
The knight's tour problem (KTP) is an interesting
mathematical problem, and its history can be dated back to
Euler and De Moivre [1]. In the past more than ten years, the
KTP has received considerable interest [2,3,4,5]. Recently,
Chia and Ong [6] initiated the study of the so-called
generalized knight’s tour problem (GKTP) by considering
the more general (a, b) move rather than the (1, 2) move. In
[7] and [8], the KTP was generalized to the 3D situation, still
with (1, 2) move. In [9] we addressed the 3D GKTP with
(a,b,c) move and proved that a chessboard of size
34 4qp×× with 2q ≥ and
2p ≥
contain a closed
generalized knight’s tour (GKT). In this paper, we
constructively prove that a chessboard of size
44
qp
×
with
3L ≥ and 4L ≠ , 2q ≥ and
2p ≥
must contain a closed
(1,2,2)-GKT. Then, we apply a closed (1,2,2)-GKT to
encrypt the video to provide a downgraded version of the
original video signal, which can be used as a preview for the
potential customers before they decide whether they want to
subscribe the services or not. This leads to the so-called
“perceptual video encryption”
[10].
II. D
EFINITIONS AND NOTATIONS
An
NML ××
chessboard is a 3-dimension array of cube
cells arranged in L rows, M columns and N levels, which are
plotted in a
y
coordinate system [9]. Without loss
of generality, we assume
LM N
≤
.
We consider the following move type on 3D
chessboards. Suppose the cells of the
MN≤≤
chessboard
are
(, , )ijk
where
01,0 1iL jM
≤− ≤≤ −
and
01kN
≤−
.
A move from cell
),,( kji
to cell
(,,)rst
is termed an
(,,)abc
- generalized knight’s move if
}
,, ,,ri s jtk abc−−−= . For a given
(,,)abc
-
generalized knight’s move on an
NML ××
chessboard,
there is associated with it a graph whose vertex set and edge
set are
{( , , ) 0 1, 0ijk i L j
≤− ≤
1, 0 1}MkN≤−≤≤−
and
{( , , )( , , ) 0 , 1;ijk rst ir L
≤−
0 , 1; 0 , 1; { , , } { , , } }
sM ktN risjtk abc≤≤−≤≤− − − −=
respectively. Let (( , , ), , , )G abc LM N denote this graph, or just
(, , )GLM N
for simplicity if the move
(,,)abc
is
understood or not to be emphasized.
A closed
(,,)abc
-generalized knight’s tour (GKT) is a
series of
(,,)abc
-generalized knight’s moves that visits
every small cube of the
NML ×
chessboard exactly once
and then returns to the starting cube. The generalized
knight’s tour problem (GKTP) asks: which
NML
chessboards admit a closed or open
(,,)abc
-generalized
knight’s tour? This amount to asking: which graph
(( , , ), , , )G abc LM N
contains a Hamiltonian cycle or a
Hamiltonian path?
There are two common tours to consider on the
rectangular parallelepiped. One is to tour the six exterior
M
,
N
, or
N
boards that form the rectangular
parallelepiped. Qing and Watkins [7] recently showed that a
(1, 2)-knight’s tour exists on the exterior of the cube
nnn
for all n. The focus of this paper is the
(,,)abc
-
generalized knight’s tour within the N stacked copies of the
M
board that form the rectangular parallelepiped, that is
the 3D chessboards.
2013 Ninth International Conference on Computational Intelligence and Security
978-1-4799-2548-3/13 $31.00 © 2013 IEEE
DOI 10.1109/CIS.2013.129
582
2013 Ninth International Conference on Computational Intelligence and Security
978-1-4799-2548-3/13 $31.00 © 2013 IEEE
DOI 10.1109/CIS.2013.129
583
2013 Ninth International Conference on Computational Intelligence and Security
978-1-4799-2548-3/13 $31.00 © 2013 IEEE
DOI 10.1109/CIS.2013.129
583
2013 Ninth International Conference on Computational Intelligence and Security
978-1-4799-2548-3/13 $31.00 © 2013 IEEE
DOI 10.1109/CIS.2013.129
583
2013 Ninth International Conference on Computational Intelligence and Security
978-1-4799-2548-3/13 $31.00 © 2013 IEEE
DOI 10.1109/CIS.2013.129
583
2013 Ninth International Conference on Computational Intelligence and Security
978-1-4799-2548-3/13 $31.00 © 2013 IEEE
DOI 10.1109/CIS.2013.129
583