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RE: [mdt-sbvr.dev] 3rd set of comments on MRV

Mark,

 

Please see comments inline below.

 

Stan

 

Mark Linehan wrote:

* Most of LFSV is missing. In particular, AtomicFormulation and RoleBinding are not implemented -- and I can't model something as simple as "Driver Bill has age 35" without those.

Right. LFSV is needed to create semantic formulations.

* Since a Text is a kind of _expression_, which is a kind of BindableTarget, I can see how the string "Bill", instantiated as a Text, can participate in an AtomicFormulation. But I don't see how a boolean true/false value or a number can be a BindableTarget. For example "Driver Bill is of age" and "Driver Bill has age 35". I think this is a problem with the SBVR spec. Comments?

A variable can be a bindable target, and the variable can range over propositions (which are true or false) or numbers. An individual concept can be a bindable target, too. One would typically bind to the individual concept designated by “Bill” rather than the _expression_ “Bill” in an atomic formulation.

* I previously commented on the use of XPATH references (rather than UUIDs) between model elements. I think it should be possible to put these individual concepts in their own XML file, separate from the model file. But separating the individual concepts from the the model itself makes it likely that one will change independently of the other. Similarly, if one SBVR vocabulary incorporates another vocabulary, it is likely that they will be kept separately and evolve independently. XPATH references between separate vocabularies will be particularly brittle.

Unfortunately, “vocabulary” is in VDBV, not MRV. Use “namespace” instead of “vocabulary” with MRV, and put different namespaces in different files. Use “namespace has URI” and “namespace1 incorporates namespace2”. Uniqueness of designations and fact type forms in namespaces is used to identify terms, names, and fact types. If designations or fact type forms are changed in subsequent versions, references will break. To maintain upward compatibility between versions of namespaces, designations and fact type forms should not be deleted, but deprecated and replaced by other terms, if a new preferred synonym is desired. Also, definitions of a term should not be changed in a new version of a released namespace unless the new definition is logically equivalent to the old one, since the term will then refer to a different concept, with unpredictable results. SBVR lacks a standard version control policy. Perhaps this project could establish some conventions to help manage this. SBVR provides fact models and conceptual schemas to separate ground facts like “Driver Bill has age 35” from the schema in separate files. Each SBVR interchange file is a fact model, including fact models that may be used as conceptual schemas. Thus “conceptual schema” is a role of a fact model in another fact model. “Fact model has URI” and “conceptual schema has URI” are not included in SBVR, so there is no SBVR standard way to uniquely identify a fact model. It would be nice to have a URI for a fact model in the standard. I think “thing has URI” should be added to the spec to provide more flexible identification and reference of model elements, particularly for managing fact model modules.

* I noticed a class "Element" in MRV that isn't used anywhere, and doesn't even have a corresponding "impl" class. I think it should be dropped.

“Element” is not defined in SBVR, but is used in the fact type “set has element”, which is a synonymous form of “thing is in set”, 8.7, p.42. See also Fig. 8.9.  I think “element” should be added to SBVR, rather than dropping “set has element,” since the latter is in the vernacular of technical people.


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