FORALL Message,Resource,Predicate,Correct <-
  problem(Message,Resource,Predicate,Correct).

FORALL Predicate,Correct,Resource
  problem("Domain constraint violation", Resource, Predicate, Correct) <-
  domainSet(Resource,Predicate,Correct),
  not domainOK(Predicate).

FORALL Predicate,Correct,Resource
  problem("Range constraint violation", Resource, Predicate, Correct) <-
  rangeSet(Resource,Predicate,Correct),
  not rangeOK(Predicate).

FORALL Predicate
  domainOK(Predicate) <-
    EXISTS Resource,Domain,Class,Value
    Predicate["http://www.w3.org/TR/1999/PR-rdf-schema-19990303#domain" ->> Domain],
    Resource["http://www.w3.org/1999/02/22-rdf-syntax-ns#type" ->> Class;
             Predicate->>Value],
    Class :: Domain.

FORALL Resource,Predicate,Class
  domainSet(Resource,Predicate,Class) <- 
    EXISTS Value
    Resource[Predicate->>Value],
    Predicate["http://www.w3.org/TR/1999/PR-rdf-schema-19990303#domain" ->> Class].

FORALL Predicate
  rangeOK(Predicate) <-
    EXISTS Resource,Range,Class,Value
    Predicate["http://www.w3.org/TR/1999/PR-rdf-schema-19990303#range" ->> Range],
    Resource[Predicate->>Value],
    Value["http://www.w3.org/1999/02/22-rdf-syntax-ns#type" ->> Class],
    Class :: Range.

FORALL Resource,Predicate,Class
  rangeSet(Resource,Predicate,Class) <- 
    EXISTS Value
    Resource[Predicate->>Value],
    Predicate["http://www.w3.org/TR/1999/PR-rdf-schema-19990303#range" ->> Class].

FORALL Object
  problem ("User-defined constraint not validated", Object, "-", "-") <-
      Object["http://www.w3.org/1999/02/22-rdf-syntax-ns#type" ->>
             "http://www.w3.org/TR/1999/PR-rdf-schema-19990303#ConstraintProperty"].

FORALL Object
  problem ("User-defined constraint not validated", Object, "-", "-") <-
      Object["http://www.w3.org/TR/1999/PR-rdf-schema-19990303#subClassOf" ->>
             "http://www.w3.org/TR/1999/PR-rdf-schema-19990303#ConstraintProperty"].

FORALL X,Y 
   X :: Y <- X["http://www.w3.org/TR/1999/PR-rdf-schema-19990303#subClassOf" ->> Y]
   OR unify (X,Y).

FORALL X,Y
  X : Y <-         
     X["http://www.w3.org/1999/02/22-rdf-syntax-ns#type" ->> Y]
  OR unify (X,Y).