![](bg8.png)
concepts in the stack stackCommon which represents
the set (O
3
∩ O
5
), 6 concept in the set (O
3
\O
5
) sto-
red in the stack stackDi f f
(O
3
\O
5
)
and 6 concepts in
the set (O
5
\O
3
) stored in the stack stackDi f f
(O
5
\O
3
)
.
After the extension of ontologies, we have respecti-
vely 18 concepts in O
0
3
and 14 concepts in O
0
5
. The
set (O
3
∩ O
5
) is extended and becomes (O
0
3
∩ O
0
5
).
(O
3
∩ O
5
) contains 11 concepts stored in the stack
stackCommonFinal. In O
0
3
, the insertions of con-
cepts have been done following this rules : in first,
”mail”, ”hosebox” and ”public transport” are inserted
as a sons of ”conveyance” (”mail” is-a ”conveyance”,
”hosebox” is-a ”conveyance” and ”public transport”
is-a ”conveyance”), and then, ”rolling stock” is in-
serted as a son of ”Wheeled vehicle” (”rolling stock”
is-a ”wheeled vehicle”). The ontology O
0
5
is exten-
ded following that ”motor” is inserted as a son of
”wheeled vehicle” (”motor” is-a ”wheeled vehicle”).
The Table 1 allows to compare the results obtai-
ned in this paper to the results of our previous works
(Ngom et al., 2017).
Table 1: Comparison of results of N
Plus
and T
Ngom
.
N
Plus
T
Ngom
(O
3
,O
4
) 0.98 0.95
(O
3
,O
5
) 0.74 0.57
In Table 1, we find that the measure N
Plus
gives
better results compared to the measure T
Ngom
. In-
deed, we have : N
Plus
(O
3
,O
4
) > T
Ngom
(O
3
,O
4
) (0.98
> 0.95) and N
Plus
(O
3
,O
5
) > T
Ngom
(O
3
,O
5
) (0.74 >
0.57). The N
Plus
measure increases the T
Ngom
mea-
sure thanks to the extension of the set of their com-
mon concepts.
6 CONCLUSION
In this paper, we proposed an approach for assessing
similarity between two ontologies. The approach that
we adopt is based on set theory, edges based semantic
similarity (Ngom., 2015) and feature-based similarity
(Tversky, 1977). It can be summarized in 5 steps. In
step 1, we have determined the sets of concepts which
characterize the concepts shared by the two ontolo-
gies and the sets of concepts that are different from
them. Once the sets have been determined, we have
assessed the average of the semantic similarity values
between concepts of each set in step 2. Step 3 is de-
dicated to the extension of ontologies. After the step
3, we have extended set of concepts that ontologies
share in Step 4. Finally, we assessed similarity be-
tween ontologies in step 5. The approach proposed
in this paper improve our proposition in (Ngom et al.,
2017) by extending the set of concepts shared by the
two ontologies. The extension on this set is realized
by taking into account the concepts of ontologies lin-
ked with concepts of the set by the ”is-a” relation. In
perspectives, we will propose an approach to assess
similarity between an ontology and a speech in text
format to check if the text and the ontology refer to
the same theme.
ACKNOWLEDGMENT
The authors would like to thank the CEA-MITIC (The
African Center of Excellence in Mathematics, Com-
puter Science and ICT) which partially funded this
work.
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