If a datum's previous certainty factor is CFp and a new rule computes a certainty factor CFn, the combined certainty factor is given by:
cfcombine(CFp, CFn) =
|CFp + CFn * (1 - CFp)||CFp > 0, CFn > 0|
|(CFp + CFn)||signs differ|
|/ (1 - min(| CFp | , | CFn |))|
|- cfcombine(- CFp, - CFn)||CFp < 0, CFn < 0|
This algorithm has a desirable feature: it is associative and commutative; therefore the result is independent of the order in which rules are considered.
A CF of + 1 or -1 is dominant and sets the combined CF to that value.
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