Advanced SA Options - Neighbourhood

During the search for rules (or solutions), moves are proposed that modify the current solution in some small way. A number of move operators are available; these are referred to as neighbourhood operators.

The selection method determines which operator to use for each proposed move. When single operator selection is used, one operator only must be selected, all other methods must have at least one operator selected.

 

Single operator

Selects a single neighbourhood operator to be performed on the current solution.

 

Random

Selects one of the neighbourhood operators at random to be performed on the current solution.

 

Probabilistic

Selects one of the neighbourhood operators probabilistically to be performed on the current solution using the set of specified probabilities.

 

Adaptive

Similar to probabilisitic selection except adaption updates the probabilities at the end of each temperature stage using the engine usage statistics. Operators that produced moves that were accepted will be promoted; those whose moves were not accepted will be demoted.

 

Adaption Rate

The rate at which adaption occurs.

 

Random Initializer

This initializer selects a starting solution by selecting at random the maximum number of allowed fields, and setting their operators and values to be random.

 

Min Values Initializer

This initializer selects a starting solution by selecting at random the maximum number of allowed fields, and setting their operators and values to be the minimum allowed values.

 

Basic Evaluator

The standard evaluator, which uses fitness as an interest measure. Reserved for future use.

 

Add percentage of range

A neighbourhood operator that increments the value in one of the selected components of a rule. The operator is cyclic so that when the maximum value in the range is reached, it will loop back to the minimum value.

The amount added to the current value is calculated as a percentage of the range of the selected field. The percentage used can be changed using the value (and spin control) to the right of the operator name.

 

Subtract percentage of range

A neighbourhood operator that decrements the value in one of the selected components of a rule. The operator is cyclic so that when the minimum value in the range is reached, it will loop back to the maximum value.

The amount subtracted from the current value is calculated as a percentage of the range of the selected field. The percentage used can be changed using the value (and spin control) to the right of the operator name.

 

Toggle selected state

A neighbourhood operator that toggles the inclusion of the current field in the rule. The maximum number of fields allowed in a rule is set on the disovery options dialog.

 

Change operator

Toggles the operator in the one of the selected rule components. For numeric fields this can be < or >; for categorical fields this will be == or !=.

 

Add percentage of range (Unselected fields)

Similar to the Add percentage of range operator, except this is applied to unselected fields only

The amount added to the current value is calculated as a percentage of the range of the selected field. The percentage used can be changed using the value (and spin control) to the right of the operator name.