Solver module produces predictive models for target variables.
Reorder rows is used to achieve uniform statistical characteristics of training and testing samples and to makes them equally informative. This technique works well for all problem types including time series models.
Options  Description 
No  Reordering is turnedoff 
Odd/even  Places all even instances after odd instances. Example: 1,2,3,4,5,6 → 1,3,5,2,4,6 
Asc.+ Odd/even  Ascending sorting of observations (by target values) prior to Odd/even reordering. 
Desc.+ Odd/even  Descending sorting of observations (by target values) prior to Odd/even reordering. 
Validation strategy is used to select a method for model validation and sorting out.
Options  Description 
Training/testing  Splits dataset into two parts, uses the training part to find model coefficients and uses the testing part to compare and select a set of the best models. 
Whole data testing  Splits dataset, trains model using the training part, but uses both parts for testing 
kfold validation  Splits dataset onto k parts, trains a model k times using k1 parts, each time measuring model performance using a new remaining part. Finally residuals obtained from all testing parts are added and used for model comparison. 
kfold training  In contrast to the kfold validation, kfold training uses k1 parts to test the model and only 1 part to estimate coefficients. In other aspects it's similar to the kfold validation. This is rather an extreme method that is used to stop overfitting when other methods do not work. 
Leaveoneout CV  This is a kfold crossvalidation with the number of folds equal to the number of observations in the dataset 
Train/test ratio is used to split the dataset into training and testing part. Percentage or exact quantities are used. For example, if we would like to split a dataset containing 200 observations using the ratio 4:1, we can apply percentage 80:20 or exact number of observations 160:40.
Defines model selection criterion for both the core algorithm and variables ranking.
Variables ranking turns on preliminary ranking and reduction of variables.
Options  Description 
No  Turnedoff 
by error (independent)  Ranking of variables according to their individual ability to predict testing data 
by usage (combinatorial)  Ranking of variables according to their importance for Combinatorial Core algorithm with limited complexity (equal to 2). Importance is calculated as the number of times the variables appear in the set of best models. 
Reduces the number of variables to n
i.e. keeps n
most important variables according to the selected ranking algorithm. Preliminary reduction of variables may reduce the quality of models, but it is definitely useful for quicker processing of highdimensional datasets.
You can select one of the available statistical learning algorithms. The description of algorithms implemented in GMDH Shell can be found in Learning algorithms
Options  Description 
Combinatorial  Best subsets regression, combinatorial search 
Neuraltype  Polynomial neural networks of GMDHtype. 
Any particular model may consist of not more than n terms.
Expands dataset with the new artificial features. Higherdimensional space frequently helps to improve the Classification and Regression models. Be careful with expanding of more than 20 initial variables because the number of all possible pairs grows fast.
Options  Description 
No  No additional variables except constant term. 
x_{i}·x_{j}  Adds all possible multiplied pairs. 
x_{i}·x_{j}, x_{j}²  Adds all possible multiplied pairs and squares. 
x_{i}·x_{j}, x_{i}/x_{j}  Adds all possible multiplied and divided pairs. Skips pairs that cause dividing by zero. 
Custom  Uses terms of custom polynomial function as new variables, see Custom polynomial 
Be aware of quick growing of memory and time consumption.
The number of initial variables  Resulting number of variables  
No  x_{i}·x_{j}  x_{i}·x_{j}, x_{i}²  x_{i}·x_{j}, x_{i}/x_{j} 

2  3  4  6  5 
3  4  7  10  10 
5  6  16  21  26 
10  11  56  66  101 
20  21  211  231  401 
50  51  1276  1326  2501 
100  101  5051  5151  10001 
200  201  20101  20301  40001 
500  501  125251  125751  250001 
The number of input variables allowed for a neuron. It is quite efficient to use two inputs for any neuron. Otherwise the computational task may become too complex.
Sets the type of the internal function for neurons. The neurons are active, i.e. each neuron can drop some of the function terms in order to increase overall predictive power of the model.
Options  Description 
a_{0} + a_{1}·x_{i} + a_{2}·x_{j}  Linear 
a_{0} + a_{1}·x_{i} + a_{2}·x_{j} + a_{3}·x_{i}·x_{j}  Polynomial 
a_{0} + a_{1}·x_{i} + a_{2}·x_{j} + a_{3}·x_{i}·x_{j} + a_{4}·x_{i}² + a_{5}·x_{j}²  Quadratic polynomial 
Custom  Uses custom polynomial function defined by user, see Custom polynomial 
Sets the upper limit for the number of network layers created by the algorithm.
Initial layer width defines how many neurons are added to the set of inputs at each new layer.
When turnedon, this option allows manual control of the number of parallel processing threads. When turnedoff, the number of threads is equal to the number of logical processors i.e. processor cores or hyperthreading cores in your PC.
You can configure a Custom polynomial function to be used for generation of Additional variables or as a Neuron function. When the 'Custom' option is selected in the corresponding list of options, a dialog window called Custom polynomial is shown.
Sets the upper limit for power of any variable in a polynomial term.
Sets the lower limit for power of any variable in a polynomial term.
For example, if Max. power is 3 and Min. power is 2, then the following terms are included to the custom polynomial: x_{1}^{3}, x_{1}^{2}, x_{1}, 1 (constant term), 1/x_{1}, 1/x_{1}^{2}. If Min. power is 1 or higher then resulting polynomial will not include a constant term.
Sets a limit for sum of absolute powers of all variables in a polynomial term.
For example, if Max total power is 3 then the following terms can be included: x_{1}*x_{2}^{2}, x_{1}*x_{2}^{2}, x_{1}*x_{2}*x_{3}, …
Sets the maximum number of variables in any polynomial term. For example, if Max. number of variables is 3, then the following terms can be included: x_{1}*x_{2}*x_{3}, (x_{1}^{2})*(x_{2}^{4})*(x_{3}^{1}) …
Here are some configuration examples for two input variables:
Max. power = 2, Min. power = 0, Max total power = 2, Max number in a term = 2 results in:
y(x_{1},x_{2}) = a_{0} + a_{1}*x_{1} + a_{2}*x_{2} + a_{3}*x_{1}*x_{2} + a_{4}*x_{1}^{2} + a_{5}*x_{2}^{2}
Max. power = 4, Min. power = 0, Max total power = 4, Max number in a term = 1 results in:
y(x_{1},x_{2}) = a_{0} + a_{1}*x_{1} + a_{2}*x_{1}^{2} + a_{3}*x_{1}^{3} + a_{4}*x_{1}^{4} + a_{5}*x_{2} + a_{6}*x_{2}^{2} + a_{7}*x_{2}^{3} + a_{8}*x_{2}^{4}