=Paper=
{{Paper
|id=None
|storemode=property
|title=Foundations on Multi-Viewpoints Ontology Alignment
|pdfUrl=https://ceur-ws.org/Vol-867/Paper22.pdf
|volume=Vol-867
|dblpUrl=https://dblp.org/rec/conf/icwit/DjakhdjakhaHB12
}}
==Foundations on Multi-Viewpoints Ontology Alignment==
https://ceur-ws.org/Vol-867/Paper22.pdf
Foundations on Multi-Viewpoints Ontology Alignment
Lynda Djakhdjakha1, 3, Mounir Hemam2, and Zizette Boufaida3
1
Department of Computer Science, University 08 May 1945 of Guelma,
Guelma 24000, Algeria
ldjakhdjakha@yahoo.fr
2
Department of Computer Science, University of Khenchela,
Khenchela 40000, Algeria
Mounir.hemam@gmail.com
3
LIRE Laboratory, Department of Computer Science,
Mentouri University of Constantine, Constantine 25000, Algeria
zboufaida@gmail.com
Abstract. In the last few years, a lot of effort has been paid to support both
consensus and heterogeneity in the same ontology. As a result, multi-
viewpoints ontologies have become essential for heterogeneous organizations
and for diverse user communities that need to share and exchange information
in an application domain. The development of multi-viewpoints ontologies by
different communities makes distributed and heterogeneous knowledge re-
sources not accessible. So, to solve this problem and in order to support users in
sharing and reusing vocabularies and knowledge, we need for techniques for
solving heterogeneity problems between different multi-viewpoints ontologies.
In this case, multi-viewpoints ontology alignment is required to provide a con-
sensual understanding of that domain represented by these ontologies. In the lit-
erature, there are much alignment systems, but existing systems are not capable
to support multiple viewpoints. So, our challenge is to introduce the notion of
multiple viewpoints in the alignment process. Therefore, in order to align multi-
viewpoints ontologies, we present in this paper first, the definition of multi-
viewpoints ontology in description logics extended by a stamping mechanism,
and then we deal with their alignment problems and definitions.
Keywords: multi-viewpoints ontology, ontologies alignement, description lo-
gics, stamping mechanism.
1 Introduction
Ontologies can apprehend, capitalize, represent, operate and share semantically
knowledge and information. However in reality, there are usually several ways to
capture the knowledge of a given domain, that is to say different viewpoints (or per-
ceptions) by which this knowledge can be represented. Thus, the same domain may
have more than one ontology, where each one is described according to a viewpoint
Proceedings ICWIT 2012 214
or a particular perception. Indeed, in a large organization, there may be several com-
munities or groups of individuals with their own viewpoints. These viewpoints de-
pend on the type of person (occupation, age, educational level, experience …) or use
(the same person may have different views depending on the task which he is trying
to accomplish) [1].
The two concepts ontology and viewpoint are complementary [2], indeed the ontol-
ogy represents the knowledge shared by multiple users and the viewpoint represents
the domain of knowledge that is relevant at a given viewpoint. With the coupling of
these tow notions we are talking about multi-viewpoints ontology. The latter gives the
same universe of discourse several partial descriptions such that each one is on a par-
ticular viewpoint.
The exploration of multi-viewpoints ontologies [1], [3-4] could be an efficient way
for heterogeneous organizations to share knowledge. The development of these ontol-
ogies by different communities makes distributed and heterogeneous knowledge re-
sources not accessible. So, to solve this problem and in order to support users in
sharing and reusing vocabularies and knowledge, we need for techniques for solving
heterogeneity problems between different multi-viewpoints ontologies. In this case,
multi-viewpoints ontology alignment is required to provide a consensual understand-
ing of that domain represented by these ontologies.
An ontology alignment is defined as a set of correspondences between ontological
entities, i.e. classes, properties, and individuals, of two ontologies [5]. In the litera-
ture, there are much alignment systems presented in [6] and [7]. However, existing
systems are not capable to support the notion of multiple viewpoints. So, our chal-
lenge is to introduce this notion in alignment process to align multi-viewpoints ontol-
ogies.
Therefore, the objective of this work is to find an alignment definition of the multi-
viewpoints ontologies described in description logics extended by a stamping mecha-
nism, and to find a definition of the semantics of these alignments. The aim of these
definitions is to be able to align multi-viewpoints ontologies.
The rest of the paper is organized as follows. Section 2 presents a multi-viewpoints
ontology. In section 3 we detail syntax and semantics of multi-viewpoints ontology
described in description logics extended by stamping mechanism. Section 4 looks at
the problems of the multi-viewpoints ontology alignment. In section 5 we present a
set of definitions for the multi-viewpoints ontology alignment, and Section 6 con-
cludes with the future directions of work.
2 Definition of Multi-Viewpoints Ontology (MVp Ontology)
2.1 Viewpoint Approach
For a given domain of knowledge, several criteria can be used to observe an object.
These different perceptions of the world are called viewpoints or perspectives. In
computer science, most of data modeling systems don’t deal with the variety of per-
ceptions related to the same universe of discourse, and develop tools to create a single
model for a single vision of the observed world. The viewpoint approach is opposed
Proceedings ICWIT 2012 215
to this monolithic approach and makes it possible to model the same reality according
to different points of view [8].
The viewpoint approach is constructed on the conjunction actor/information. There-
fore, it is necessary to include the actor in the action. In [9] viewpoint is defined as “a
conceptual manner binding, on the one hand an actor who observes and, on the other
hand, a universe of discourse which is observed”.
2.2 Multi-Viewpoints Ontology
A multi-viewpoints ontology is defined as an ontology in which a concept can have
multiple definitions, each definition corresponding to a particular viewpoint on the
concept [1], [3].
In [4], a multi-representation ontology is seen as an ontology that characterizes an
ontological concept by a variable set of properties (static and dynamic) or attributes in
several contexts and granularities.
The accepted definition in our work is that mentioned in [2] and [8], where a multi-
viewpoints ontology is defined as an ontology that gives the same universe of dis-
course, several partial descriptions, in a way that, each one is on one viewpoint. These
partial descriptions share on a global level the ontological elements (concepts and
global roles) and semantic links constitute a consensus between the different view-
points.
3 A Multi-Viewpoints Ontology in Description Logics Extended
by a Stamping Mechanism
Description logics (DL) [10-11] are a family of knowledge representation languages
that can be used to represent the knowledge of an application domain in a structured
and formally well-understood way. A stamping mechanism allows multiple represen-
tations of concepts. In [2] and [8], description logics extended by a stamping mecha-
nism have a signature, which is based on the following types: global concepts, local
concepts, global roles, local roles, individuals and bridge rules. This language allows
the use of constructors to create complex elements.
Definition 1 (Multi-viewpoints Ontology in Description Logics Extended by a
Stamping Mechanism). A multi-viewpoints ontology described in description logics
extended by a stamping mechanism is a multiple descriptions of the same universe of
discourse according to different viewpoints. It is defined as the quadruple
, , , where: : is a set of global concepts, : is a set of global roles,
: is a set of bridge rules and : is a set of viewpoints, where a viewpoint is a par-
tial description of a universe of discourse in a particular perception. It is defined by
the triplet , , , where: : is a set of local concepts, : is a set of local roles
and : is a set of local individuals.
Proceedings ICWIT 2012 216
Definition 2 (Syntax of a Global Concept). Given ,…, ,…, a set
of viewpoints. A global concept can be formed using the Boolean manufacturers
(conjunction, disjunction) and the following global restrictions manufacturers:
• ,…., . , ,…., . : defines a new concept that all their instances are
connected by the role ,
• ,…., . , ,…., . : specifies the minimum or maximum cardinality
of the role in the viewpoints .
Definition 3 (Syntax of a Local Concept). Given . A local concept
: is either a primitive local concept or a defined local concept:
: . .
. . , , … , where and are local concepts, is
a local Role, , , … are individuals, and is a natural number.
Definition 4 (Syntax of a Local Role). A given local role : is defined as:
: , , where is the name of the local role defined in the viewpoint ,
are two local concepts defined in this viewpoint . As well, a local role
can be a primitive local role or a defined local role: , , ,
° and , , where are given local roles.
Definition 5 (Syntax of a Global Role). A global role is defined as:
: , : , where is the name of the global role, are two
local concepts defined in two different viewpoints. As well as a local role, a global
role can be a primitive or a defined global role.
Definition 6 (Syntax of a Subsumption Relation). Below a viewpoint , a local
hierarchy / , is defined as a triplet , , where: is a set of local con-
cepts, is a function of in , witch associated for all root concept denoted of
a global concept of , and is the subsumption relation used to express explicit-
ly a direct order relationships as follows:
• : : , where and are two local concepts defined in the same
viewpoint .
• : , where is the most general concept defined in the viewpoint ,
and is a global concept.
Definition 7 (syntax of a Bridge Rule). We distinguish:
• Inclusion. : : . It expresses the set inclusion between a local concept
extension of a viewpoint and another concept of another viewpoint.
Proceedings ICWIT 2012 217
• Inclusion with Multiple Sources. : … : .It expresses an inclu-
sion relation between a list of local concepts belonging to several viewpoints and
another destination concept belonging to another viewpoint.
• Bidirectional Inclusion. : : . It expresses equality between two local
concepts belonging to two different viewpoints.
• Bidirectional Exclusion. : : . It expresses a relationship between two
local concepts belonging to two different viewpoints.
3.1 Semantics of Multi-Viewpoints Ontology
In [2] and [8], the semantics of description logics extended by the stamping mecha-
nism is defined by a global interpretation, a set of local interpretations, and a set of
domain relations:
Definition 8 (Local Interpretation). A local interpretation ∆ , . ), is associated for
each local element, where ∆ is a domain of local interpretation and . I is a local
interpretation function such that for all local concepts of , ∆ , for all local
roles , ∆ ∆ , and for all individuals , ∆ .
Definition 9 (Global Interpretation). A global interpretation ∆ , . ) is associated for
each global element, where ∆ ∆ … ∆ … ∆ is a domain of global interpreta-
tion and . is a global interpretation function such that for all global concepts ,
∆ , for all global role , ∆ ∆.
Definition 10 (Domain Relation). A relation domain defines how two different
viewpoints interact.
4 The problems of Multi-Viewpoints Ontology Alignment
In this work, we will take into consideration the notion of viewpoint in the alignment
process. Thus, the multi-viewpoints ontologies alignment is the task to find the rela-
tionships that hold between the entities belonging to these ontologies.
Multi-viewpoints ontologies cover different domains that can be modeled different-
ly and can represent several viewpoints. They can support both heterogeneity (at a
local level) and consensus (at a global level). In the multi-viewpoints ontologies
alignment, there is a great heterogeneity resides in the variations present in the seman-
tic coverage of comparable concepts, especially local concepts that are defined ac-
cording to different viewpoints and that can be semantically very similar. Indeed, the
mapping task or alignment task between multi-viewpoints ontologies is more difficult
than that between classical ontologies, because there is much specificity for this pro-
cess. Among the specificities of multi-viewpoints ontologies alignment, we may find:
Proceedings ICWIT 2012 218
4.1 Elements to Align
In the alignment process between classical ontologies, the task is to discover corre-
spondences between concepts, properties and individuals. In our context of multi-
viewpoints ontologies described in description logic extended by stamping mecha-
nism, it is necessary to take into account the different types of concepts (global and
local), the different types of roles (global and local), individuals.
4.2 Localization of Local Elements According to the Different Viewpoints
In our context, there are two description types: a global description and other partial
descriptions defined according to different viewpoints. So, taking into account the
localization of the local concept (local role) in the alignment process influenced on
the remaining correspondences that can be discovered.
4.3 Bridge Rules
The consideration of bridges rules between elements of different viewpoints impact
on the set of correspondences found.
5 Multi-Viewpoints Ontologies Alignment
We adopt the definitions of classical ontology alignment presented in [12] and [13], to
define the MVp ontology alignment.
Definition 11 (MVp Ontology Alignment). Given , two multi-
viewpoints ontologies in description logics extended by a stamping mechanism. An
alignment between , is defined as the task to find the best subset of the
correspondences between multi-viewpoints ontology elements belonging to
and .
Definition 12 (MVp Ontology Element). A multi-viewpoints ontology element is a
term of the multi-viewpoints ontology (e.g., global concept, local concept, global role,
local role or individual).
Definition 13 (Correspondences). Given , ′ two multi-viewpoints ontol-
ogies in description logics extended by a stamping mechanism, a correspondence
between , ′ is defined as a triple , ′ , where:
and are multi-viewpoints ontology elements from the two multi-
viewpoints ontologies to align, and is a relation that is asserted to hold
tween ′
Multi-viewpoints ontologies alignment contains correspondences between global
concepts, local concepts, global roles, local roles or between individuals belonging to
these ontologies. These correspondences are similar to the bridge rules in a same mul-
Proceedings ICWIT 2012 219
ti-viewpoints ontology. We can identify the different types of correspondences be-
tween two multi-viewpoints ontologies i and j as follows: i: C G j: DG , i: C L j: DL ,
i: C L j: DG , i: RG j: S G , i: RL j: S L , i: RL j: S G , i: C G j: DG , i: C L j: DL ,
i: C L j: DG , i: RG j: S G , i: RL j: S L , i: RL j: S G , i: a j: C G , i: a j: C L ,
i: a j: b , where C G and DG are global concepts, C L and DL are local concepts,
RG and SG are global roles, RL and SL are local roles, a and b are individuals, is a
subsumption relation , is a disjunction relation , is a membership relation, and
is a identity relation.
Consequently, a multi-viewpoints ontology alignment involves a set of entities con-
nected by symbols of relations. It is seen as a pair , , where is a set
of entities described in description logics extended by a stamping mechanism. And
is a set of symbol of relationships between these entities. So, it is necessary to
interpret the pair , before interpreting a multi-viewpoints ontology
alignment.
Definition 14 (Entities Interpretation). Interpretation of entities is a pair ∆ , . ),
where ∆ is a domain of interpretation and . is an interpretation function such that for
all local concepts , ∆ , for all global concepts , ∆ , for all local
roles , ∆ ∆ , for all global roles , ∆ ∆ , and for all individuals ,
∆ , where∆ is a local domain of interpretation and it is a subset of ∆ .
Definition 15 (Multi-Viewpoints Ontologies Alignment Interpretation). In our
context, all entities are coming from the same description language. An interpretation
of an alignment relation between two multi-viewpoints ontologies is a
pair ∆ . , . ), where ∆ is a global domain of interpretation and . is a binary relation
of interpretation such that for all relations , ∆ ∆ , where ∆ and
∆ are domain of interpretation of the multi-viewpoints ontologies respective-
ly, and are subsets from∆ . Each multi-viewpoints ontology has its own domain of
interpretation.
6 Conclusion
In this paper, we specified the basic concepts that constitute a starting point for multi-
viewpoints ontology alignment.
Several research directions are considered to carry out this work. We will use these
definitions to propose a method of multi-viewpoints ontology alignment. We, also,
plan to include bridge rules between multi-viewpoints ontologies elements for the
reasoning on the multi-viewpoints ontologies and alignments in order to obtain the
best set of alignments between these ontologies.
Proceedings ICWIT 2012 220
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