// ################### FLORA SPECIFIC #########################
// Integrity Constraint to enforce signatures:
// If there is an instance X of Class, that has an Attribute Y and
// there is a signature definition corresponding to "Attribute" then
// Y has to be an instance of RangeofAttribute

// This is actually questionable. Should this treated relaxed or
// strict, i.e. is a fact invalid when it does not explicit state 
// that one of the attribute values belongs to the coressponding range defintion
// or should it be infered that the attribute value is member of the range given in the signature
//
Y:Range :- 
  X:Class, X[Attribute->Y], Class[Attribute=>Range],
  (Class=date;Class=time;Class=dateAndTime).

// Integrity Constraint to invalidate instance not corresponding to a signature:
// If there is an instance X of Class, that has an Attribute Y and
// there is NO signature definition corresponding to Attribute then
// X is invalid
X[valid(Attribute)] :- X:Class, X[Attribute->_Value], Class[Attribute=>_Range].
invalid(X, Y) :- 
  X:Class, X[Attribute->_Value], tnot X[valid(Attribute)], 
  Y = 'no signature for ' + Attribute + ' in Class ' + Class.

invalid(X) :- invalid(X,_Y).