The New Hybrid COAW Method for Solving Multi-Objective Problems

International Journal in Foundations of Computer Science & Technology (IJFCST) Vol.5, No.6, November 2015
DOI:10.5121/ijfcst.2015.5602 15
THE NEW HYBRID COAW METHOD FOR SOLVING
MULTI-OBJECTIVE PROBLEMS
Zeinab Borhanifar and Elham Shadkam*
Department of Industrial Engineering, Faculty of Eng.; Khayyam University, Mashhad,
Iran
ABSTRACT
In this article using Cuckoo Optimization Algorithm and simple additive weighting method the hybrid
COAW algorithm is presented to solve multi-objective problems. Cuckoo algorithm is an efficient and
structured method for solving nonlinear continuous problems. The created Pareto frontiers of the COAW
proposed algorithm are exact and have good dispersion. This method has a high speed in finding the
Pareto frontiers and identifies the beginning and end points of Pareto frontiers properly. In order to
validation the proposed algorithm, several experimental problems were analyzed. The results of which
indicate the proper effectiveness of COAW algorithm for solving multi-objective problems.
KEYWORDS
Cuckoo Optimization Algorithm (COA), simple additive weighting (SAW), Pareto frontier, Multi-objective
optimization problem (MOP).
1. INTRODUCTION
There are many methods for solving nonlinear constrained programming problems such as
Newton, Genetic algorithm, the algorithm of birds and so on. In this paper using the emerging
Cuckoo Optimization Algorithm and simple additive weighting a method to solve multi-objective
problems is presented.
In single-objective optimization, it is assumed that the decision makers communicate only with
one goal like: profit maximization, cost minimization, waste minimization, share minimization
and so on. But in the real world it is not possible to consider single goals and usually more than
one goal are examined. For example, in the control of the projects if only the time factor is
considered, other objectives such as cost and quality are ignored and the results are not reliable.
So it is necessary to use multi-objective optimization problems.
Ehrgott and Gandibleux presented a detailed approximation method regarding the problems
related to combinatorial multi-objective optimization [1]. Klein and Hannan for multiple
objective integer linear programming problems (MOILP) presented and algorithm in which some
additional restrictions is used to remove the known dominant solutions [2]. Sylva and Crema
offered a method to find the set of dominant vectors in multiple objective integer linear
programming problems [3]. Arakawa et al. used combined general data envelopment analysis and
Genetic Algorithm to produce efficient frontier in multi-objective optimization problems [4].
Deb analyzed the solution of multi-objective problems by evolutionary algorithms [5]. Reyes-
seerra and Coello Coello analyzed the solution of multi-objective problems by particle swarm [6].
Cooper et al. have worked on the solution of multi-objective problems by the DEA and presenting

16
an application [7]. Pham and Ghanbarzadeh solved multi-objective problems by bee algorithm
[8]. Nebro et al. analyzed a new method based on particle swarm algorithm for solving multi-
objective optimization problems [9]. Gorjestani et al. proposed a COA multi objective algorithm
using DEA method [10].
For multi-objective optimization problems usually it is not possible to obtain the optimal solution
that simultaneously optimizes all the targets in question. Therefore we should try to find good
solutions rather than the optimal ones known as Pareto frontier. Given that so far the Simple
Additive Weighting method is not used in meta-heuristic, especially cuckoo algorithms, this
paper presents a combined method.
The first section introduces Cuckoo optimization algorithm, then in the second section Simple
Additive Weighting (SAW) method is discussed as a combined method for solving multi-
objective described. Finally, the fourth section provides the proposed implemented approach,
numerical results and a comparison which is made with other methods.
2. CUCKOO OPTIMIZATION ALGORITHM
Cuckoo optimization algorithm was developed by Xin-She Yang and Suash Deb in 2009. Thence
Cuckoo optimization algorithm was presented by Ramin Rajabioun in 2011 [11]. Cuckoo
algorithm flowchart is as figure 1. This algorithm applied in several researches such as production
planning problem [12], portfolio selection problem [13], evaluation of organization efficiency
[14], evaluation of COA [15] and so on. For more information about the algorithm refer to [11].
3. SIMPLE ADDITIVE WEIGHTING METHOD
SAW is one of the most practical methods designed for decision-making with multiple criteria
presented by Hong and Eun in 1981. In this method which is also known as weighted linear
combination after scaling the decision matrix by weighted coefficients of criteria, the free scale
weighted decision matrix id obtained and according to this scale the score of each option is
selected. The most important feature of this method is the simple application because of its
mathematical logic.
Assuming the multiple target model (1) and defining the parameters w1 and w2 which are the
weight of the objective functions and defined based on the importance of the functions by the
decision maker, the model can be converted to single-objective models (2):
Max F(x)=( , , … . ,
(1)
s.t. ≤
≥ 0
Max F(x)= + + ⋯ +
(2)
+ + ⋯ + = 1
In these models x … x are objective functions. is the weight defined by the importance
of the decision maker.

Figure 1: The
4. PRESENTATION OF HYBRID
In this section we present the method
algorithm are as follows. Also the flowchart of COAW algorithm is as figure 2.
Step1 Different random w1 and w
equals to one.
Step 2 The present locations of Cuckoos are determined randomly
Step 3 A number of eggs are allocated to each Cuckoo
Step 4 The laying radius of each Cucko
Step 5 The Cuckoos hatch in the nests of the hosts that
Step 6 Eggs that are detected by the host birds are destroyed
Step 7 The eggs of the identified cuckoos are nurtured
Step 8 The habitats of the new cuckoos are evaluated by SAW method and determined weights
Step 9 the maximum number of cuckoos living at each location are determined and the on
wrong areas are destroyed
Step 10 The cuckoos are clustered by K
the residence
Step 11 The new population of cuckoos m
Step 12 Stop condition is established otherwise go to step 2
determined for the best solutions and the Pareto frontier is gained based on
The Cuckoo optimization algorithm flowchart
HYBRID COAW ALGORITHM
In this section we present the method COAW which is proposed in this paper. The steps of this
algorithm are as follows. Also the flowchart of COAW algorithm is as figure 2.
and w2 are generated subject to the summation of these two values
Cuckoos are determined randomly
gs are allocated to each Cuckoo
ch Cuckoo is determined
Step 5 The Cuckoos hatch in the nests of the hosts that are within their laying radius
by the host birds are destroyed
identified cuckoos are nurtured
new cuckoos are evaluated by SAW method and determined weights
Step 9 the maximum number of cuckoos living at each location are determined and the on
Step 10 The cuckoos are clustered by K-means and the best cluster of cuckoos is determined as
Step 11 The new population of cuckoos moves toward the target location
ablished otherwise go to step 2Step 13 the value of
determined for the best solutions and the Pareto frontier is gained based on ,
17
in this paper. The steps of this
are generated subject to the summation of these two values
new cuckoos are evaluated by SAW method and determined weights
Step 9 the maximum number of cuckoos living at each location are determined and the ones in
is determined as
Step 13 the value of , are

Figure 2. The flowchart of COAW algorithm
5. IMPLEMENTATION OF COAW
In this section in order to validat
problems are presented in Table 1.
Number of problem
1
2
3
SAW module
Determination of
weights problem
Evaluation of cost
function based on
determined weights
Figure 2. The flowchart of COAW algorithm
COAW ALGORITHM ON SOME TEST PROBLEM
In this section in order to validation the COAW algorithm some test problems are analyzed.
esented in Table 1.
Table 1. Test problems
Constraints
Objectives
2 + 2 4
, ≥ 0
=
=
1 + ≤ 0
, ≥ 0
= 2
=
3 ≤ 0
≥ 1, ≤ 2
=
=
18
PROBLEMS
problems are analyzed. Test
4 ≤ 0

19
Given that determining input parameters is one of the effective problems in meta-heuristic
algorithms, so the parameters of the algorithm are presented as follows: the number of initial
population=5, minimum number of eggs for each cuckoo= 2, maximum number of eggs for each
cuckoo =4, maximum iterations of the Cuckoo Algorithm=50, number of clusters that we want to
make=1, Lambda variable in COA paper=5, accuracy in answer is needed=-3.75, maximum
number of cuckoos that can live at the same time=10, Control parameter of egg laying=5,
cuckooPopVariance = 1e-13.
6. THE SOLUTION OF TEST PROBLEMS
In this section the experimental problems of the previous section are solved by the proposed
algorithm and the results are compared and examined with the same algorithm.
6.1. The First Problem
Figure 3. Pareto frontiers created by COAW algorithm for first problem
(C)
(b)
(a)
Figure 4. Pareto frontiers created by: (a) Ranking method (b) DEA method (c) GDEA Method for first
problem
0 0.5 1 1.5 2 2.5
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
f1
f2

20
6.2. The Second Problem
Figure 5. Pareto frontiers created by COAW for the first problem
(c)
(b)
(a)
Figure 6. Pareto frontiers created by: (a) Ranking method (b) DEA method (c) GDEA Method for second
problem
6.3. The Third Problem
Figure 7. Pareto frontiers established by COAW for third problem
-1 -0.5 0 0.5 1 1.5 2 2.5
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
f1
f2
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
f1
f2

21
(C)
(b)
(a)
Figure 8. Pareto frontiers created by: (a) Ranking method (b) DEA method (c) GDEA Method for third
problem
After the implementation of the proposed approach on test problems the Pareto frontiers are
obtained according to figures 3, 5 and 7 in order to compare the COAW method with other
methods, ranking method, DEA method and GDEA method are implemented on problems. The
results are show as figures 4, 5 and 8.
As figures indicate the created Pareto frontiers of the COAW proposed algorithm are exact and
have good dispersion. This method has a high speed in finding the Pareto frontiers and identifies
the beginning and end points of Pareto frontiers properly. The COAW algorithm not only solves
the problems with lower initial population 5 but also it presents better and more exact answers in
fewer repetitions than similar methods.
7. CONCLUSION
In this paper the hybrid COAW algorithm was presented to solve multi-objective problems. The
hybrid approach includes Cuckoo Algorithm and Simple Additive Weighting method. The
algorithm was analyzed for a number of experimental problems and compared with several
similar methods. The results indicate the accuracy in finding Pareto frontiers. Also the Pareto
frontier is better than similar methods and as a result COAW proposed method is reliable, fast and
simple to solve multi-objective optimization problems.
REFERENCES
[1] Ehrgott, M., Gandibleux, X., Bound Sets for Bi objective Combinatorial Optimization Problems,
Computers & Operations Research, Vol. 34, Issue 9, 2674-2694, 2007.
[2] Klein, D., Hannan, E., An Algorithm for the Multiple Objective Integer Linear Programming
Problem, European Journal of Operational Research, 1982, 9, 378–385.
[3] Sylva, J., Crema, A., A Method for Finding the Set of Non-Dominated Vectors for Multiple Objective
Integer Linear Programs, European Journal of Operational Research, 158, pp. 46–55, 2004.
[4] Arakawa, M., Nakayama, H., Hagiwara, I., Yamakawa, H., Multiobjective Optimization using
adaptive range genetic algorithms with data envelopment analysis, Vol.3, 1998.
[5] Deb, K., Multi-Objective Optimization using Evolutionary Algorithms, John & Wiley Sons, Ltd.,
2001.
[6] Reyes-Sierra, M., Coello Coello, CA., Multiple objective particle swarm optimizers: A survey of the
state-of-art. International Journal of Computational Intelligence Research 2(3), 287–308, 2006.
[7] Cooper, W.W., Seiford, L.M., Tone, K., Data Envelopment Analysis: A Comprehensive Text with
Models, Applications, References and DEA Solver Software. Springer, New York, 2007.

22
[8] Pham, DT., Ghanbarzadeh, A., Multi-objective optimization using the bees algorithm. In: Third
international virtual conference on intelligent production machines and systems (IPROMS 2007):
Whittles, Dunbeath, Scotland, 2007.
[9] Nebro, A.J., Durillo, J.J., Garc´ıa-Nieto, J., Coello Coello, CA., Luna F and Alba E (2009) SMPSO:
A new PSO-based metaheuristic for multi-objective optimization. 2009 IEEE Symposium on
Computational Intelligence in Multi criteria Decision-Making (MCDM 2009). IEEE Press, New
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[10] Gorjestani, M., Shadkam, E., Parvizi, M., Aminzadegan, S., A HYBRID COA-DEA METHOD FOR
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[11] Rajabioun, R., Cuckoo Optimization Algorithm, Applied Soft Computing, Vol. 1, pp 5508–5518,
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[12] Akbarzadeh, A., Shadkam, E., THE STUDY OF CUCKOO OPTIMIZATION ALGORITHM FOR
PRODUCTION PLANNING PROBLEM, International Journal of Computer-Aided technologies,
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[13] Shadkam, E., Delavari, R., Memariani, F., Poursaleh, M., PORTFOLIO SELECTION BY THE
MEANS OF CUCKOO OPTIMIZATION ALGORITHM, International Journal on Computational
Sciences & Applications, Vol.5, No.3, 2015.
[14] Shadkam E., Bijari M., The Optimization of Bank Branches Efficiency by Means of Response
Surface Method and Data Envelopment Analysis: A Case of Iran, Journal of Asian Finance,
Economics and Business Vol. 2 No. 2, 13-18, 2015.
[15] Shadkam E., Bijari M., EVALUATION THE EFFICIENCY OF CUCKOO OPTIMIZATION
ALGORITHM, International Journal on Computational Sciences & Applications. Vol.4, No.2, pp. 39-
47, 2014.

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