Organizations: Department of Engineering, University of Toyama, Toyama-shi 930-8555, Japan · Cyberscience Center, Tohoku University, Sendai-shi 980-8578, Japan · Faculty of Science and Technology, Hirosaki University, Hirosaki-shi 036-8560, Japan · Sino-German College of Applied Sciences, Tongji University, Shanghai 200092, China · School of Mechanical Engineering, Tongji University, Shanghai 200092, China · Chongqing Institute of Microelectronics Industry Technology, University of Electronic Science and Technology of China, Chongqing 401332, China · Artificial Intelligence and Big Data College, Chongqing Polytechnic University of Electronic Technology, Chongqing 401331, China · Department of Information Engineering, Yantai Vocational College, Yantai 264670, China
Constrained single-objective numerical optimisation requires both feasibility maintenance and strong objective-value convergence under limited evaluation budgets. This report documents RDEx-CSOP, a constrained differential evolution variant used in the IEEE CEC 2025 numerical optimisation competition (C06 special session). RDEx-CSOP combines success-history parameter adaptation with an exploitation-biased hybrid search and an ε-constraint handling mechanism with a time-varying threshold. We evaluate RDEx-CSOP on the official CEC 2025 CSOP benchmark using the U-score framework (Speed, Accuracy, and Constraint categories). The results show that RDEx-CSOP achieves the highest total score and the best average rank among all released comparison algorithms, mainly through strong speed and competitive constraint-handling performance across the 28 benchmark functions.
Figures & tables
Rank
Algorithm
Total Score
Avg Score/Prob.
Speed
Accuracy
Constraint
1
RDEx-CSOP
53680.5
1917.16
44437.0
3440.0
5803.5
2
RDEx
49155.0
1755.54
39695.5
3730.5
5729.0
3
UDEIII
30545.0
1090.89
22368.5
3093.0
5083.5
4
CL-SRDE
28805.5
1028.77
19673.0
3245.5
5887.0
TABLE I: CEC 2025 CSOP evaluation (median target): overall scores over 28 problems and 25 runs for all released comparison algorithms.
Competitor
Final Q
TTT
W/T/L
Holm
A12
W/T/L
Holm
A12
RDEx
1/26/1
1/27/0
0.52
4/24/0
1/27/0
0.58
UDEIII
16/4/8
15/5/8
0.84
19/3/6
19/3/6
0.89
CL-SRDE
6/18/4
6/19/3
0.50
24/4/0
23/5/0
0.92
TABLE II: Primary pairwise summary over the 28 CEC2025 CSOP functions (25 runs). We report uncorrected per-function Wilcoxon W/T/L at α=0.05 , Holm-corrected W/T/L across functions, and the median Vargha–Delaney A12 effect size for feasibility-aware final quality and time-to-target (larger is better for minimization).
Algorithm
Final Q
TTT
RDEx-CSOP
2.29
1.61
RDEx
2.39
2.14
UDEIII
2.84
2.89
CL-SRDE
2.48
3.36
TABLE III: Primary Friedman tests on per-function medians over the 28 CEC2025 CSOP functions (25 runs). Final Q: χ2=2.90 , df=3 , p=0.408 ; TTT: χ2=30.47 , df=3 , p=2.62E−06 . Lower average rank indicates better performance.
Appendix figures & tables8 assets
Supplementary material from the paper’s appendix.
Appendix
Rank
Algorithm
Total Rank
Avg Rank/Prob.
Avg Speed
Avg Accuracy
Avg Constraint
1
RDEx-CSOP
38.0
1.36
1.59
2.75
2.52
2
RDEx
63.0
2.25
2.20
2.30
2.52
3
UDEIII
83.0
2.96
2.89
2.48
2.41
4
CL-SRDE
96.0
3.43
3.32
2.46
2.55
Appendix
TABLE IV: CEC 2025 CSOP evaluation (median target): average rankings over 28 problems (lower is better) for all released comparison algorithms.
Problem
RDEx-CSOP
RDEx
UDEIII
CL-SRDE
Mean
SD
Mean
SD
W
Mean
SD
W
Mean
SD
W
1
3.27E-30
4.75E-30
5.92E-30
9.27E-30
=
1.57E-28
9.70E-29
+
1.26E-31
6.18E-31
=
2
3.74E-30
5.62E-30
3.04E-30
4.86E-30
=
1.31E-28
7.83E-29
+
7.24E-31
2.42E-30
=
3
2.56E+02
7.36E+01
3.39E+02
1.63E+02
=
9.22E+01
5.54E+01
-
5.37E+02
1.07E+02
+
4
1.54E+01
1.42E+00
1.57E+01
1.45E+00
=
6.51E+00
6.78E+00
-
4.84E+01
8.86E+00
+
5
0.00E+00
0.00E+00
0.00E+00
0.00E+00
=
1.17E-28
4.17E-28
=
0.00E+00
0.00E+00
=
Appendix
TABLE V: Feasibility-aware final-quality comparison on the 28 CEC2025 CSOP functions. For each run, the final-quality score equals the final objective/IGD value for feasible runs and Bp+CV for infeasible runs, where Bp is the largest finite final objective/IGD value on problem p plus 1 (smaller is better).
Problem
RDEx-CSOP
RDEx
UDEIII
CL-SRDE
Mean
SD
Mean
SD
W
Mean
SD
W
Mean
SD
W
1
1332.6
546.2
1382.6
548.3
=
1979.6
105.0
+
1327.4
137.8
=
2
1251.2
514.8
1298.5
527.0
=
1960.7
138.2
+
1399.3
222.3
+
3
1575.3
541.4
1813.9
272.3
=
394.8
162.1
-
2001.0
0.0
+
4
1607.4
529.8
1569.9
496.5
=
837.6
50.4
-
2001.0
0.0
+
5
986.2
12.0
986.6
13.9
=
1476.4
466.1
+
1395.2
14.8
+
Appendix
TABLE VI: Time-to-target comparison on the 28 CEC2025 CSOP functions. TTT is the first checkpoint index where the run reaches the median target (smaller is better); runs that never reach the target are assigned 2001.
Competitor
Final Obj.
Final CV
AUC
W/T/L
Holm
A12
W/T/L
Holm
A12
W/T/L
Holm
A12
RDEx
1/27/0
1/27/0
0.54
1/26/1
0/28/0
0.50
1/27/0
1/27/0
0.55
UDEIII
14/7/7
14/7/7
0.73
22/5/1
21/6/1
1.00
15/4/9
14/6/8
0.73
CL-SRDE
10/16/2
10/17/1
0.51
2/22/4
2/22/4
0.50
28/0/0
28/0/0
1.00
Appendix
TABLE VII: Complementary pairwise summary over the 28 CEC2025 CSOP functions (25 runs). For each metric (Final Obj., Final CV, and AUC), we report uncorrected per-function Wilcoxon W/T/L at α=0.05 , Holm-corrected W/T/L across functions, and the median Vargha–Delaney A12 effect size (larger is better for minimization).
Algorithm
Final Obj.
Final CV
AUC
RDEx-CSOP
2.11
2.21
1.75
RDEx
2.46
2.20
1.96
UDEIII
2.66
3.62
2.57
CL-SRDE
2.77
1.96
3.71
Appendix
TABLE VIII: Complementary Friedman tests on per-function medians over the 28 CEC2025 CSOP functions (25 runs). Final Obj.: χ2=4.25 , df=3 , p=0.234 ; Final CV: χ2=29.00 , df=3 , p=4.82E−06 ; AUC: χ2=39.13 , df=3 , p=7.74E−08 . Lower average rank indicates better performance for each metric.
Problem
RDEx-CSOP
RDEx
UDEIII
CL-SRDE
Mean
SD
Mean
SD
W
Mean
SD
W
Mean
SD
W
1
3.27E-30
4.75E-30
5.92E-30
9.27E-30
=
1.57E-28
9.70E-29
+
1.26E-31
6.18E-31
=
2
3.74E-30
5.62E-30
3.04E-30
4.86E-30
=
1.31E-28
7.83E-29
+
7.24E-31
2.42E-30
=
3
2.56E+02
7.36E+01
3.39E+02
1.63E+02
=
9.22E+01
5.54E+01
-
5.37E+02
1.07E+02
+
4
1.54E+01
1.42E+00
1.57E+01
1.45E+00
=
6.51E+00
6.78E+00
-
4.84E+01
8.86E+00
+
5
0.00E+00
0.00E+00
0.00E+00
0.00E+00
=
1.17E-28
4.17E-28
=
0.00E+00
0.00E+00
=
Appendix
TABLE IX: Final objective comparison on the 28 CEC2025 CSOP functions. For each algorithm, the mean and SD over 25 runs are reported; W gives the Wilcoxon outcome of RDEx-CSOP against the competitor.
Problem
RDEx-CSOP
RDEx
UDEIII
CL-SRDE
Mean
SD
Mean
SD
W
Mean
SD
W
Mean
SD
W
1
-2.70E+05
0.00E+00
-2.70E+05
0.00E+00
=
0.00E+00
0.00E+00
+
-2.70E+05
0.00E+00
=
2
-2.70E+05
0.00E+00
-2.70E+05
0.00E+00
=
0.00E+00
0.00E+00
+
-2.70E+05
0.00E+00
=
3
-1.99E+05
1.85E+04
-1.85E+05
1.90E+04
+
0.00E+00
0.00E+00
+
-1.52E+05
2.11E+04
+
4
-4.45E+00
3.34E+00
-5.01E+00
3.12E+00
=
0.00E+00
0.00E+00
+
-2.01E+01
3.74E+00
-
5
-2.14E+03
0.00E+00
-2.14E+03
0.00E+00
=
0.00E+00
0.00E+00
+
-2.14E+03
0.00E+00
=
Appendix
TABLE X: Final constraint-violation comparison on the 28 CEC2025 CSOP functions. For each algorithm, the mean and SD over 25 runs are reported; W gives the Wilcoxon outcome of RDEx-CSOP against the competitor.
Problem
RDEx-CSOP
RDEx
UDEIII
CL-SRDE
Mean
SD
Mean
SD
W
Mean
SD
W
Mean
SD
W
1
0.17
0.01
0.17
0.00
=
0.14
0.01
-
0.32
0.01
+
2
0.20
0.01
0.20
0.01
=
0.14
0.01
-
0.38
0.01
+
3
1.87
0.65
2.18
0.50
=
0.50
0.18
-
3.15
0.11
+
4
0.78
0.24
0.84
0.32
=
0.81
0.04
=
1.80
0.08
+
5
0.36
0.01
0.36
0.01
=
0.30
0.01
-
0.60
0.02
+
Appendix
TABLE XI: Anytime convergence comparison using AUC over 2000 checkpoints on the 28 CEC2025 CSOP functions. For each run, AUC is computed as the mean of log10(1+max(ft−TGT,0)) across checkpoints (smaller is better).
Department of Engineering, University of Toyama, Toyama-shi 930-8555, Japan · Cyberscience Center, Tohoku University, Sendai-shi 980-8578, Japan · Faculty of Science and Technology, Hirosaki University, Hirosaki-shi 036-8560, Japan +5
Department of Engineering, University of Toyama, Toyama-shi 930-8555, Japan · Cyberscience Center, Tohoku University, Sendai-shi 980-8578, Japan · Faculty of Science and Technology, Hirosaki University, Hirosaki-shi 036-8560, Japan +5