Database Reference
In-Depth Information
has_sequence
has_destination
Merea Highway
Road Segment 1
Merea City
next_segment
has_destination
Road Segment 2
Ash Fleet
next_segment
has_destination
Road Segment 3
Medina
FIGURE 10.6
n
-ary relations: Merea Highway's road segment sequences.
These three examples all create individuals belonging to anonymous classes,
and we have not given meaningful names to either the individuals or those classes
because they are never used on their own, but only as part of the pattern to model the
n
-ary relation. Therefore, there is no reason to invent a distinguishing name.
4. When the relationship links several objects in an implied sequence. For
example, Merea Highway goes through Merea City, Ash Fleet Village, and
Medina. This use case cannot follow the same pattern as the aforementioned
use cases as we need to describe the sequential nature of the cities reached
by the highway. In OWL Full, the RDF List object could be used, but for
OWL DL we require the structure in Figure 10.6.
10.4.4.5.1 Value Partitions and Value Sets
The value partitions and value sets of patterns are useful when you want to model
adjectives or other modifiers, for example, an “expensive beer” or a “three-star pub,”
where there are only a limited number of choices (e.g., “cheap,” “moderate,” and
“expensive”). In OWL, there are a few ways to approach this, either as a partition of
classes (known as a “value partition”):
Beer is a Concept.
Porter, Bitter, Stout, Lager, and
Ale are Concepts.
Every Beer is exactly one of
Porter or Bitter or Stout or
Lager or Ale.
Porter, Bitter, Stout, Lager, and
Ale are mutually exclusive.
Class: Beer
DisjointUnionOf: Porter, Bitter,
Stout, Lager, Ale
or at the individual level, known as “a value set”, by enumerating the individuals or
listing all the values using datatype properties:
PubRating is a Concept.
Every PubRating is exactly one of
onestar or twostar or threestar.
onestar, twostar and threestar
are different things.
Class: PubRating
ObjectOneOf: onestar, twostar,
threestar
DifferentIndividuals: onestar,
twostar, threestar
