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  • Implicit disjunctive mandatory constraint

    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 ...
    Posted to ORM Techniques (Forum) by Matt Nizol on Wed, Apr 1 2015
  • Transitive implication in a subtype graph

    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? ...
    Posted to NORMA (Forum) by Matt Nizol on Sat, Mar 28 2015
  • Re: Model elements that are not displayed on any diagram

    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? ...
    Posted to NORMA (Forum) by Matt Nizol on Fri, Mar 13 2015
  • Model elements that are not displayed on any diagram

    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 ...
    Posted to NORMA (Forum) by Matt Nizol on Tue, Mar 10 2015
  • Re: Subset constraint terminology

     Thank you!  That's a very helpful way of thinking about the "simple" qualifier.  "Simple subset constraint" it is.  Matt 
    Posted to ORM Techniques (Forum) by Matt Nizol on Wed, Aug 27 2014
  • Re: Subset constraint terminology

    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 ...
    Posted to ORM Techniques (Forum) by Matt Nizol on Wed, Aug 27 2014
  • Subset constraint terminology

    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 ...
    Posted to ORM Techniques (Forum) by Matt Nizol on Wed, Aug 27 2014
  • Role value constraints in ORM2

    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 
    Posted to ORM Techniques (Forum) by Matt Nizol on Tue, Aug 12 2014
  • Spanning Role Value Constraint

    May a value constraint span multiple roles in ORM?  Examples in the "Big Brown Book" seem to cover only one role.  Consider the below example.  If the example constraint is invalid, might an alternative be to objectify the spanned roles and then apply a value constraint to the objectified type? Best, Matt   
    Posted to ORM Techniques (Forum) by Matt Nizol on Wed, Mar 26 2014
  • Re: Population validation on a join subset constraint

    Does any tool (separate from NORMA) exist to check whether a sample population satisfies all constraints in an ORM model? Thanks, Matt
    Posted to NORMA (Forum) by Matt Nizol on Wed, Feb 12 2014
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