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Hybridizing biogeography-based optimization and integer programming for solving the travelling tournament ...

                                   ·10 5      NL 16                 ·10 5      NL 14
                              4.55                             2.92
                            quality  4.5                        2.9



                            solution  4.45                     2.88



                                                               2.86
                                    8     10   12    14   16             8     10    12     14
                                               Ft                               Ft


                                      Figure 5. Influence of Ft on the travel cost value

                                              NL 12                   4       NL 10
                                      5
                                   ·10                             ·10
                                                                8.5
                               1.65
                             quality


                             solution  1.6                        8



                               1.55
                                                                7.5
                                        6      8     10    12            4      6       8
                                                Ft                              Ft


                                      Figure 6. Influence of Ft on the travel cost value.


                                                                               NL 14
                                            NL 16

                            6,000                             2,000

                           Time(s)  4,000                     1,000


                            2,000


                                0                                 0
                                      8    10    12   14              6     8      10    12
                                              Ft                                 Ft

                                          Figure 7. Influence of Ft on the runtime

            benchmarks. As indicated, our method outper-      CON 16 , CON 14 , CON 12 , CON 22 , and CON 4 .
            forms the current best solutions reported in 12   Additionally, the Average Gap (AG) for CON
            for NL 16 . Moreover our approach successfully    instances is AG(CON) = 0.38%, demonstrating
                                                              that our results are highly aligned with the opti-
            achieves the best-known results for NL 4 , NL 6 ,
                                                              mal solutions, showing only a 0.38% deviation.
            NL 8 , NL 10 , and NL 12 .
                The results demonstrate that our new ap-
                                                                  To evaluate the performance of our approach
            proach successfully attains the optimal solution
                                                              in solving the Traveling Tournament Problem
            for instances CON 24 , CON 10 , CON 8 , CON 6 ,
                                                              (TTP),we carried out a detailed comparison
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