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In-Depth Information
that dereference to it.
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No document is considered authoritative for literals,
though this has little effect on the reasoning process.
Authoritative reasoning is applied over a Linked Dataset as given in Defini-
tion 1, which tracks the source associated with each RDF graph. Furthermore,
the algorithm requires knowledge about redirects to establish the authoritative
function. In practice, these data are replicated locally for the reasoning engine
to access; the reasoner does not perform live lookups.
Authoritative Reasoning.
The primary goal of the authoritative reasoning pro-
cess is to safe-guard widely used vocabularies from redefinition in arbitrary lo-
cations. Precise definitions and guarantees for authoritative reasoning are given
elsewhere in [38,12]. Here sketching the main intuition, given an ontology
O
providing a set of T-Box axioms and
G
an arbitrary RDF graph (e.g., a Web
document or a merge of documents), if
G
does not mention any term for which
O
is authoritative, and
O
is not an implicit import of such a document, then we
do not want the
T-Box axioms
provided by
O
to affect materialisation over
G
.
Thus, for example, if
G
instantiates vocabulary terms from the FOAF ontology
but not from the DBpedia ontology, then the T-Box extracted from DBpedia
should not affect inferencing over the A-Box of
G
. The implicit imports of the
FOAF ontology can, however, affect inferencing over the T-Box of
G
,eveniftheir
terms are not explicitly mentioned. For example, the FOAF ontology states that
foaf:Person
is a sub-class of
geo:SpatialThing
;if
G
contains instances of
foaf:Person
, they will be inferred to be instances of
geo:SpatialThing
and it
will then be the prerogative of the corresponding WGS84 Geo Ontology to define
what inferences are possible over the latter class, even though the corresponding
class is not explicitly referenced by
G
.
Whether or not a T-Box axiom is considered authoritative then directly de-
pends on the rules being applied in the reasoning process. In fact, a T-Box axiom
may be authoritative with respect to one rule and not another.
Example 9
Take the following T-Box triple from Fig. 1:
dbo:Person owl:equivalentClass foaf:Person .
This triple is given by the document that
dbo:Person
dereferences to. If
we then take OWL 2 RL/RDF rule
cax-eqc1
mentionedinExample8:
(?
C
1
,
owl:equivalentClass
,
?
C
2
)
,
(?
X,
a
,
?
C
1
)
the T-Box triple is authoritative for this rule since it translates data about
dbo:Person
instances into
foaf:Person
instances.
(?
X,
a
,
?
C
2
)
←
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The source URI will often not share the namespace of the URIs it is authoritative
for since redirects (esp. PURLS) are commonly used for dereferencing schemes.
