Information Technology Reference
In-Depth Information
The compatibility between two
Date
concepts is given by the following function:
fcomp
{
“
Date
}
(
c
1
,
c
2
)=
sim
type
(
t
1
,
t
2
)
∗
sim
ref
num
(
v
1
,
v
2
)
>
0
and
• sim
ref
num
(
)=
|
−
|≥
v
1
,
v
2
0if
v
1
v
2
5
−
|
d
1
−
d
2
5
otherwise
With sim
type
defined in 5.14, page 20 and sim
ref
num
defined above.
v
1
and
v
2
are numeric values expressing the dates in numbers of minutes. For instance, the
27th of November 2006 at 6.45 am, written “2006.11.27.06.45.00” in the figures depicting the
example graphs is expressed as: 200611270645.
• sim
ref
num
(
v
1
,
v
2
)=
1
5.4.4 Definition of the fusion function
The fusion function allows, for any couple of concept nodes, to process, if it exists, the concept
node resulting from the fusion of the two initial nodes:
Definition 5.15.
The function
f
fusion
:
2
C
→C
is defined as follows:
f
fusion
(
)=
c
1
,
c
2
c
∈C
where c
is the concept that results from the fusion of c
1
and c
2
.
For instance, when fusing two “Text” concepts, we may choose to keep the longest of the two
compatible string values.
5.4.5 Extension of the maximal join operation
The fusion strategies are used to extend the maximal join operation that was initially defined
by Sowa. The notion of compatibility between two concept nodes is extended and the
construction of the joint (i.e. fused) concepts is also modified, allowing to use the fusion
function. We call this extension “
maximal join given a fusion strategy
”.
Fig. 14. Compatible concepts given a fusion strategy
Two concepts are compatible (Figure 14) if
• they have a most general common sub-type, and
• their values conform this most general common sub-type,
• they are compatible given the selected compatibility function.
The fusion of two concepts is a concept with their most general common sub-type as type, and
the result of the fusion function applied to their values as value.
To process the compatibility of two relation nodes, we consider their types and the
neighboring concepts. Their types must be identical, and the concepts must be compatible
pair wise, respecting the labels of the edges that link them to the relations.
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