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Modeling

(See initial modeling discussion here)

We are basically going to implement the following conversion approach. See at the end for remaining questions.

Unit class

An instance of the Unit class captures one main unit entry in the XML. It may have a primary name (via property hasName) and zero or more aliases (via hasAlias property).

UnitName class

Instances of the UnitName class capture names and aliases associated with instances of a class Unit.

hasDefinition property

This is a functional property to capture the <def> element from the XML description.

hasName property

This is a functional property that indicates the primary name of a given Unit instance. In particular, a unit may not have a primary name.

hasAlias property

Indicates an alternate name for a given Unit instance. A unit can have zero or more aliases associated.

hasSymbol property

Indicates a symbol associated with a given Unit instance. A unit can have zero or more symbols associated.

namesUnit property

With UnitName as domain, this functional property indicates the Unit instance associated with the name.

hasCardinality property

With UnitName as domain, this functional property indicates whether the name is "singular" or "plural".

Remarks:

• The approach clearly separates the concept of unit from any associated specific names/aliases.
• Those names/aliases will have URIs per se (so they could be self-resolvable)
• The hasSymbol property could also be used as a property of UnitName in cases where the symbol is for the specific name.

Example

The following entry from the original vocabulary:

        <unit>
            <def>'/60</def>
            <name><singular>arc_second</singular></name>
            <symbol>"</symbol>
            <symbol>&#x2033;</symbol>           <!-- DOUBLE PRIME -->
            <aliases>
                <name><singular>angular_second</singular></name>
                <name><singular>arcsecond</singular></name>
                <name><singular>arcsec</singular></name>
            </aliases>
        </unit>

will result in the RDF representation:

@prefix :        <http://mmisw.org/ont/mmitest/udunits2-accepted/> .
@prefix prop:    <http://mmisw.org/ont/mmitest/udunits2-prop/> .

:2a1369 
      a                      :Unit ;
      prop:hasDefinition     "'/60" ;
      prop:hasName           "arc_second" ;
      prop:hasAlias          :arcsec, :angular_second, :arcsecond ;
      prop:hasSymbol         "\"", "″" ;

:arc_second
      a                      :UnitName ;
      prop:namesUnit         :2a1369;
      prop:hasCardinality    "singular";

:arcsec
      a                      :UnitName ;
      prop:namesUnit         :2a1369;
      prop:hasCardinality    "singular";

:angular_second
      a                      :UnitName ;
      prop:namesUnit         :2a1369;
      prop:hasCardinality    "singular";

:arcsecond
      a                      :UnitName ;
      prop:namesUnit         :2a1369;
      prop:hasCardinality    "singular";

Remaining questions to proceed with implementation:

1. Assuming both Unit and UnitName instance URIs will share the same namespace, how to determine the id for each Unit instance in a way that is "stable", that is, that will be preserved even upon multiple conversions as the original vocabularies are updated?

Possible strategy:

• Unless so manual ID assignment is desired, we could apply some arbitrary but deterministic translation of the given primary name.

Any other questions?