In the Rainbird Studio  weight is used to express which conditions in a rule are more relevant or importantThe weighting of a rule’s conditions contribute to the certainty of the fact that a rule infers, but weight should not be confused with the certainty factor of a fact or rule. The certainty of a rule is impacted by the weighting of conditions that have been satisfied and the certainty of any relevant facts.

The weights of all conditions in a rule are summed together and the weight for each condition will represent the proportion that condition affects the certainty factor. For example if we have a rule with two conditions, each of which have weight equal to 100, then our total is 200. Each condition contributes 50% of the total wight of the rule:

Figure 1: A rule with two conditions, each with an equal weight

If however one condition is weighted at 100 and the other is 50, then the total would be 150. The first condition would contribute 66% of the total weight and the second only 33%.

Figure 2: A rule with two conditions, each having a different weight

Conditions assigned a weight of 0 have no impact on the certainty of the fact or facts that a rule infers. This means that, regardless of whether or not the condition is satisfied, the condition will not affect the certainty of the new fact. The reason having conditions with 0 weight is that a relationship needs to be considered but has no impact on the certainty of the decision.

For example in our hello world example there are three conditions in the rule ‘speaks language’:

Figure 3: ‘Speaks language’ relationship rules

The first and second conditions born in and lives are the basis for our decision on what language the person may speak. The third condition ‘has national language’ relates to the country’s language rather than the person’s. It is important that Rainbird knows the languages of the country but it does not affect what language the person speaks, therefore it is set at weight 0.

Figure 4: Conditions with a weighting of 0 as they appear in the salience view 

It does not matter what the total weight of the rule is (as long as its greater than 0) and the weights in one rule will not affect the weights in another.

Weight can be 0 or any positive number. By default, a condition is assigned a weight of 100 but knowledge authors can adjust this value accordingly. Within a rule, conditions with the most weighting have the greatest impact on the overall certainty of the new fact that a rule infers. 

For more information on Weight, click here to watch a Rainbird training video.


Click on the ‘Export.rbird’ button to download the ‘Weight’ map used in this example. The knowledge map can then be imported into your Rainbird Studio.

Query and Results

The query is built on the relationship speaks language. The query outcome will show what language a person speaks depending on the country they were born in.

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Version 1.01 – Last Update: 16/02/2021