*4.1. Stepwise Feature Selection Process*

The process of stepwise feature selection is to select a feature from the unselected feature set each time and add the feature set S. In accordance with the selection order, the feature set outputs an ordered feature sequence.

When initializing, the feature set is empty. The unselected feature set is the complete set of all known features.

After each step selection, the feature set increases the feature set selected in this step, while the feature set not selected reduces the feature set selected in this step. Until the unselected feature set is empty.
