Constraints allow to define pieces of information that are forbidden in the facts (negative constraints) or mandatory in the facts (positive constraints).

To create a new constraint or edit an existing constraint go on the projects view  and use the popup menu (right-click).


You will find all the information about the use of the constraints are in section Inspecting facts


Create a new constraint:

Select the type of Constraint that you want to add in your project:

 


Negative constraints


A negative constraint is a simple graph expressing a condition that must not appear in checked facts. Checking a negative constraint is similar to query facts. Facts are validated if no homomorphism of the constraint graph can be found into them.

no wine is sweet and strong ?

Positive constraints

A positive constraint is a structured as a rule with a condition part and the obligation part. A fact satisfies a positive constraint if every homomorphism from the condition part to the fact can be extended to a homomorphism of the obligation part to the fact. The example below expresses the fact that "a wine is necessarily associated with a winery". Positive constraints will be triggered each time a wine appears without a Winery attached to it with hasMaker relation.


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