The ORM Foundation

Hi Terry, By "FBM metamodel", are you referring to the work discussed here: http://www.factbasedmodeling.org/objectives.aspx?  Has the core of the metamodel (excluding dynamic rules) been published somewhere?    Thanks, Matt 

Hi Terry and Matt, Thank you very much for your responses.  Below is my new understanding of the implicit disjunctive mandatory constraint:If some object type: Is primitiveIs non-independentPlays at least one non-existential roleHas no non-existential roles covered by a simple or disjunctive mandatory constraint Then all of that ...

Per pages 161 and 164 of the BBB, primitive entity types must play at least one reference role and at least one fact role.  I'd like to clarify a couple details about this rule in ORM: (1) Are the roles played by an entity type in a compound reference scheme considered reference roles? (2) Per page 246, this rule doesn't apply to ...

In NORMA, suppose I create three object types (A, B, C) and declare that: A is a subtype of BB is a subtype of CA is a subtype of CIn this situation, NORMA reports an error message stating that "Direct supertypes...must be overlapping without transitive implication."  Why does transitive implication warrant an error message? ...

Hi Terry and Matt, Thank you both for your responses.  The ORM Shape Missing group type is very helpful---I was unaware of that capability.  Do you think it would make sense to change the default settings such that NORMA warns the user of elements that aren't displayed unless the user explicitly suppresses that warning message? ...

Is there a practical use case for including elements in a model that aren't displayed on any diagram?  NORMA permits this by providing a choice of whether to delete the underlying model element when deleting the model element's final shape from a diagram.  Because the answer to this choice defaults to "No", I wonder if ...

 Thank you!  That's a very helpful way of thinking about the "simple" qualifier.  "Simple subset constraint" it is.  Matt 

Thanks, Matt.  Given the standard use of "simple" to qualify internal uniqueness constraints that cover one role and non-disjunctive mandatory constraints, I also had thought that "simple" would be a reasonable qualifier for the type of subset constraint in question.  However, I don't see "simple subset ...

Is there a standard qualifier to distinguish a subset constraint that covers exactly one subset role and one superset role from other forms of the constraint?  In the BBB, I see the terms "pair-subset", "tuple-subset", and "join-subset" used to distinguish more complex forms of the constraint.  Is it ...

My understanding from reading http://www.orm.net/pdf/ORM2.pdf is that role value constraints were introduced in ORM version 2; thus, value constraints in ORM version 1 applied only to object types.  Can someone confirm?   Thanks, Matt