The syntax of constraints is similar to the syntax of queries. A constraint is considered violated if a result is yielded when the constraint is posed as a query.
The syntax is:
Example of constraints:
!- ?X:person[worksAt -> ?C:company, hasJob -> false].
This constraint asserts that if a person works at a company, then it is not possible that this person has no job, namely that the value of the attribute “has job” is “false”.