Information Technology Reference
In-Depth Information
wb:annotatesValueOf
associates slot
t
with slot
s
.Theslots
s
and
t
have val-
ues
v
s
and
v
t
. For these annotations, webble vocabulary defines the following
entailment rule
R
1
.
(
wb
:
hasValue
,v
t
)
∈
An
(
t
)
∧
(
wb
:
represents
,p
)
∈
An
(
t
)
∧
(
wb
:
annotatesValueOf
,s
)
∈
An
(
t
)
∧
(
wb
:
hasValue
,v
s
)
∈
An
(
s
)
(
p, v
t
)
∈
An
(
v
s
)
R
1
: Slot value annotation
By
R
1
, the annotations in Figure 5 entails annotation (
p,v
t
)
An
(
v
s
), which is
illustrated as the dashed line arrow in the figure. The role of this entailment rule
R
1
is to
lift
slot annotations to slot
value
annotations. By using this mechanism,
we can annotate media
contents
indicated by slot values.
Now we are ready to annotate contents specified by
url
slot. However, at
present,
url
slot of DublinCoreWebble
wm
has no value. To get the url of the
image displayed by the image webble
wi
, we can use webble composition and the
slot connection mechanism. By combining
wm
with
wi
as a child, and connecting
both
url
slots, the
url
slot of
wm
gets a url from
url
slot of
wi
.Asaresult,the
annotation of
wm
's
url
slot gets the following attribute-value pair.
∈
-
An(wm:#url) =
{
..., (wb:hasValue, http://a/b/c.jpeg)
}
Then, we apply entailment rule
R
1
to associate slot values with annotations of
slot values. In this example, rule
R
1
matches with
s
=
wi:#url
,
t
=
wm:#url
,
v
s
=
http://a/b/c.jpeg
,
v
t
=
"La Joconde"
,
p
=
dc:title
.Asaresult,thisexam-
ple annotation entails
(dc:title, "La Joconde")
∈
An(http://a/b/c.jpeg)
.
It is exactly an annotation of the image
http://a/b/c.jpeg
.
As we demonstrated here, our framework uses
wb:hasValue
,
wb:represents
,
wb:annotatesValueOf
, and entailment rule
R
1
to associate slot values to anno-
tations. These three terms and one rule form the core of the webble vocabulary.
The full definition of the webble annotation core vocabulary can be found in the
appendix.
2.3 Mapping Annotations to RDF Graphs
Conceptually a webble annotation is just a set of attribute-value pairs. However,
by restricting attribute names to be only RDF properties, we can easily map
webble annotations to RDF graphs. The basic idea is that we can represent an
attribute-value pair (
a, v
) in annotation
An
(
i
) as an RDF statement “
iav
”if
a
is an RDF property.
Table 1 shows the mapping from webbles and webble annotations to RDF
graphs used in our framework. In our approach, each webble and each of its
slots is mapped to an RDF resource. Static structure (ownership of slots, etc.),
dynamic state (slot values) and annotations are mapped to RDF statements.
The graph in figure 6 shows an RDF representation of the example that we use
in this section. In this graph, statements mapped from webble annotations are
