Parameter Optimization - Gene Expression Programming - page 312

Table 8.2
Settings for the simple optimization problem using the GEP-PO algorithm.

Number of generations 50

Population size 20

Function set + - * /

Terminal set ?

Random constants array length 5

Random constants type Rational

Random constants range [-2, 2]

Head length 5

Gene length 17

Number of genes 1

Chromosome length 17

Mutation rate 0.044

Inversion rate 0.1

IS transposition rate 0.1

RIS transposition rate 0.1

One-point recombination rate 0.3

Two-point recombination rate 0.3

Random constants mutation rate 0.55

Dc-specific mutation rate 0.044

Dc-specific inversion rate 0.1

Dc-specific transposition rate 0.1

encoding a parameter value that corresponds to the global maximum of func-
tion (8.4) was created in generation 6.
The initial population of this run, including both the structures and out-
puts of all its individuals, is shown below (a dash is used to flag the outputs
that fall outside the chosen domain [-1, 2]; these individuals are all unviable
and therefore have zero fitness):

GENERATION N: 0
Structures:
+-?+???????000141-[ 0]- {-0.633606, 1.44528, -1.92072, 0.232788, -0.41391}
**//+??????211123-[ 1]- {1.20468, -0.64856, -1.20969, -0.706726, -1.00031}
/?+//??????243140-[ 2]- {0.801392, 0.965424, -0.887329, -1.9809, -1.3096}
**/-*??????140233-[ 3]- {0.344513, -1.6423, 1.91223, -0.810486, -0.187408}
-+?*/??????124212-[ 4]- {-1.44888, 0.859101, -0.359344, 0.763397, -1.00958}
*?**???????210103-[ 5]- {-1.08029, 0.391937, -0.400848, -1.36026, -1.73004}
-*+/+??????420324-[ 6]- {-0.908265, 1.15857, -0.871125, -0.459991, -0.345245}
/----??????022212-[ 7]- {1.88175, -0.858857, -0.51532, 0.108032, 0.486572}