RelRig anti-pattern

Full name

Relator Mediating Rigid Types


Logical; Scope




A «Relator» connected to one or more rigid types through mediations.


When a type is connected to a mediation association, it means that it is externally dependent, i.e. for an individual to instantiate it, it must be related to another type. Usually, mediations define roles and roleMixins – anti-rigid types.

  1. Let relator(m) and mediated(m) be the functions that return, respectively, the relator and the mediated types connected to a mediation. Also, let M be the set of mediation-n and R the set of RigidType-n, then:

    \[\forall m \in M, relator(m) = Relator \ \land \ mediated(m) \in R\]
  2. Let mediatedEnd(m) be the function that returns the association end connected to the mediated type of a given mediation m, isReadOnly(p) the function that return the value of the isReadOnly meta-property of an association end p and M the set of the identified mediations, then:

    \[\forall m \in M, isReadOnly(mediatedEnd(m)) = true\]


Refactoring Plans
  1. [Mod/New] Set as role: choose this plan when a RigidType-n should be anti-rigid. If previously stereotype with a sortal stereotype, change it to role, if non-sortal, change to «RoleMixin». (If RigidType-n was stereotyped as «Kind», «Collective» or «Quantity», a new identity provider should be created for it using the same stereotype). RefactoringPlan1

  2. [New/Mod] Add role subtype: choose this action if the mediation-n is optional for RigidType-n. Create a «Role» (for sortals) or a «RoleMixin» (for non-sortals) that specializes RigidType-n and move mediation-n to it. RefactoringPlan2

  3. [Mod] Set as mode: choose this plan when RigidType-n is in fact an unstructured property of Relator-n. This is only true if the existential dependency specified in the mediation is reversed (RigidType-n should depend on «Relator» and not the other way around)

  4. [Mod] Set bidirectional existential dependency: choose this action if the event that creates the Relator is the same one that creates RigidType-n and also this relation established in the individuals creation may never change.


Prince Sales, Tiago. (2014). Ontology Validation for Managers.