=Paper=
{{Paper
|id=Vol-552/paper-5
|storemode=property
|title=From Subjects to Concept Clouds - Why semantic mapping is necessary
|pdfUrl=https://ceur-ws.org/Vol-552/Thomas-et-al-KF08.pdf
|volume=Vol-552
}}
==From Subjects to Concept Clouds - Why semantic mapping is necessary==
https://ceur-ws.org/Vol-552/Thomas-et-al-KF08.pdf
From Subjects to Concept Clouds –
Why semantic mapping is necessary
Hendrik Thomas1 , Bernd Markscheffel2 , Tobias Redmann2
1 Chair of Information- and Knowledge Management, TechnischeUniversität Ilmenau,
P.O. Box 100565, 98693 Ilmenau, Germany 2 Knowledge / Data Engineering Group,
School of Computer Science and Statistics, Trinity College Dublin, Ireland
{thomash}@cs.tcd.ie {bernd.markscheffel,tobias.redmann}@tu-ilmenau.de
Abstract. To realize the vision of the semantic web it is essential to be
able to exchange formal modeled knowledge between applications and
humans without loss of meaning. In this paper, we focus on questions
relating to meaning, interpretation and subject identity in modern se-
mantic web languages. Based on the semiotic triangle we show that topics
as well as RDF resources are symbols, representing concepts and not ref-
erents as the common term “subject” would indicate. A subject can not
be represented as a single entity, but rather as a complex and evolving
system of different concepts. Based on this insight we explain how the
resulting plurality and uncertainness of the interpretation of symbols can
be handled using semantic mappings. By defining transformation rules,
the exchange and integration of knowledge from different semantic mod-
els becomes possible. Concluding we define recommendations and design
guidelines for a semantic mapping management system, which is needed
to support users and applications in creating, reusing, managing and
applying such semantic mappings.
1 Introduction
Tim Berners-Lee described in 2001 a use-case, where digital agents are able to
arrange appointments collaboratively by searching various information vaults
based on personal preferences and contextual information [1]. This well-known
vision of Tim Berners-Lee is often used to explain what the World Wide Web
will or at least should look like in order to support us in dealing with the complex
and dynamic world of today [2].
One key challenges of the semantic web[2] is the expression of knowledge
to enable a flexible exchange between users and software applications without
loss of meaning [3, 4]. This implies that knowledge may be made available to
applications other than those for which it was originally created. Sophisticated
semantic technologies like the Resource Description Framework (RDF)[5], the
Web Ontology Language (OWL)[6] or Topic Maps[7] can be used to formal
model knowledge implicit and explicit contained in web content [2, 4]. The mod-
eling of knowledge is inescapably bound to meaning and semantic aspects [8, 9].
To provide efficient mechanisms for communication and knowledge exchange, it
is necessary to have a detailed understanding of how a statement about a sub-
ject is made, interpreted by the recipient and how meaning is established [10,
11]. However, research and discussion in the semantic web community seems to
be dominated by technical and syntactical questions [2, 3]. Existing literature
discussing the semantic principles of, e.g. Topic Maps or RDF, and how to con-
nect it with existing theories of indexing, knowledge organization and semiotics
is quite rare [8, 9, 11].
In this paper we will address these open questions by pointing out, what it
might be about the semantic nature of semantic modeling that should, at the
very least, be taken into account. Therefore we will focus in section two on the
conceptual similarities between RDF[5] and Topic Maps[7]. In section three we
discuss the semantic triangle in order to explain the factors involved whenever
any statement is made or understood. In section four we discuss the implica-
tion of this insight on RDF and Topic Maps, especially in regard to the subject
identity question [11]. In the next sections we will explain how the identified
problems can be addressed by using semantic mappings. In section six we will
conclude recommendations and design guidelines for a semantic mapping man-
agement system, which is needed to support users and applications in creating,
reusing, managing and applying semantic mappings. The paper concludes with
a summary and an outlook.
2 Subjects in Topic Maps and RDF
RDF and Topic Maps are common technologies for the formal encoding of knowl-
edge [2, 7]. Despite the obvious technological and conceptual differences (e.g.
languages, implementations, structure, elements)[12], we can note that there are
significant similarities between the two with regard to semantics.
1. Usage of symbols
Both technologies use special symbols or indices to represent the relevant
subject of interest in their digital worlds (see Fig. 1). In Topic Maps these
symbols are called topics [7] and in RDF resources [3]. Both act as proxies for
the ineffable subjects of the real world in order to formally model statements
about them [11]. The subject can be anything whatsoever, regardless of
whether it exists or not [7]. In particular, it is anything which the creator
chooses to discourse.
2. One symbol per subject
The common goal of RDF as well as Topic Maps is to ensure that every
subject is represented by one or more common symbols [4, 13]. Thus a topic or
a RDF resource can be used as “binding point” for everything that is known
about a given subject. If someone searches an information, he just have to
find the right symbol (topic or RDF resource) representing the searched
subject, and than he can access all subject related information [3, 4, 12].
However, this implies the common accepted assumption, that equal symbols
represent the same subject [5, 7]. For example, if a user or an application
finds two equal RDF resources in different semantic models, the user can
http://sample.ie/driver
http://sample.ie/has
http://sample.ie/car
»ressource in a RDF graph«
driver »subject«
has
car
»topics in a topic map«
Fig. 1. Using symbols to represent subjects in Topic Maps and RDF
assume that both represent the same subject and all modeled information
are relevant for the same subject [14].
3. URIs are used to define the subject identity
The question is, how can we formally identify a symbol (topic or RDF re-
source), thus describing its subject identity. Each topic as well as each RDF
resource contains an Uniform Resource Identifier (URI) [3, 7, 11, 14]. The
URI or more commonly URL (as a subclass of URIs) can be used to identify
any subject. As a result, if two symbols share the same URI they are con-
sidered identical by humans as well as by applications [12, 14]. Thus RDF as
well as Topic Maps expects two symbols with the same URI to be referring
to the same thing.1
In summary we can note, that Topic Maps and RDF uses a surprisingly
similar approach for modeling knowledge. The cores of both technologies are
symbols and URI’s to represent subjects.
3 Making a Statement
What is a subject in regard to semantics and how is it interpreted by the user to
create meaning?[8] To deal with this question, the standard documents of Topic
1
Please note, Topic Maps defined two special scenarios in this context [7, 14]. First,
a URI can be used as reference to a subject indicator resource in an attempt to
unambiguously identify the subject represented by a topic to a human being. In
other word the referred resource describes the represented topic. Second, the URI
refers to the information resource that is the subject of the topic. The topic thus
represents that particular information resource, e.g. a topic represents the web page
http://www.dublin.ie. In RDF this distinction is not modeled explicit and has to be
handled by the user or application [15].
Maps and RDF are not very helpful. In RDF the subject is simply define as “An
entity; anything in the universe”[15] and in Topic Maps “anything whatsoever,
regardless of whether it exists or has any other specific characteristics, about
which anything whatsoever may be asserted by any means whatsoever” [7]. These
very general explanation are not very meaningful, because the relation between
the symbol and the represented thing is not defined explicitly [8].
For a better understanding it is helpful to view this question in the light of
literature on semiotics. In particular the semiotic triangle[10, 16], which is also
known as the triangle of reference, triangle of meaning and concept triangle,
provide a valuable insight (see Fig. 2). This triangle figure has its genesis, in
a diagram used by Ogden and Richards to explain the three factors involved
whenever any statement is made or understood [16]. The basic elements of every
»concept«
http://sample.ie/car
»referent« »symbol«
Fig. 2. Semiotic triangle
communication are the specific objects of the real or abstract world, which we
like to talk about. In the semiotic triangle these are called referents or objects [8,
16, 17]. Every referent possesses an individual amount of attributes and charac-
teristics. However, a user considers only the relevant characteristics and ignores
the rest depending on his own interest, current situation or perspective [10]. For
example, if a user wants to buy a car, he will probably consider the configura-
tion, the mileage and the price. However, for most users the name of the person
who installed the steering-wheel or the metal alloy used for the roof of the car is
circumstantial. In general, there are endless attributes for every referent, but it
is only the essential characteristics that define an object for a human. It is this
ability of humans to differentiate between essential and non essential character-
istics, which allows us to deal with our complex world and to communicate [10].
The sum of the essential characteristics of a referent is called concept or refer-
ence. This thought reflects the inner image of the relevant object, every human
creates unconsciously [16, 17] It is highly subjective and depends on the context
of the user, [8] e.g. for a person who works on an office desk, the weight is not
relevant, but for a furniture remover it is, because of his profession. To enable
a clear communication with others, we need to express these concepts by using
appropriate symbols, like names, textual definitions, pictures, sounds, etc.[8, 17,
25] The symbols have to be defined in the community and must be suitable to
highlight the relevant characteristics in order to allow a user to understand the
meaning, e.g. a ISBN number is common symbol for a book.
Textual symbols can be split in the group of lexical and non-lexical expres-
sions [17]. Lexical expressions are a defined term or a term combination for a
specific concept. It allows a compact identification, e.g. AIDS is a common ac-
cepted term for the complex clinical pattern of the acquired immune deficiency
syndrome. In contrast for many concepts a single name is not available and
therefore a paraphrasing description is needed, e.g. aquaplaning describes a sit-
uation when a road get slippery during rain. But there is no single lexical term
to describe, if a floor gets slippery by milk. To sum up the semiotic triangle
consists of the following three elements [8]:
– referent, is the specific object of the real or abstract world, we what to talk
about
– concept, is the thoughts of the object, that a human has in his mind of the
referent
– symbol, is an expression of the concept which are used to communicate with
others
Considering the relationships between these elements, we must note that there is
a direct (almost causal) relationship between the referent and a concept, because
the concept is a subset of the overall characteristics of the referent. User can have
different concept of the same referent but normally they share at least some
characteristics, which enable them to communication, even if it is reduced to the
common denominator, e.g. a designer, assembly line worker and customer may
not share the same view on a car but in a communication they are able to talk
about the same thing.
Furthermore there is a less direct relationship between concept and symbol.
In the end, any symbol can be chosen which (at least from the perspective of
the creator) is suitable to encode the concept. Representing a concept in natural
language or in an image can produce an infinity of variation. Hence, it is an
inherently indeterminate process 2 and yields an unpredictable result [17].
Finally, there is only a indirect relationship between symbol and referent.
In other words, there is no way of determining how any given symbol, refers
to any given object of relevance [8]. In particular Heidegger explains that 3
a relationship between a symbol and referent exists relative to the needs of
the acting individual: where one person might perceive a concept of a specific
kind, another might perceive a concept of a different kind[31], or not perceive
any concept at all, because the situation lacks relevance [8, 18]. For example, in
2
An indeterminate process is one which can proceed in an infinity of variations so
that its progress is rendered unpredictable [17].
3
A detailed analysis of the philosophical interpretation of symbols and meaning of
the philosophers Pierce and Heidegger can be found in [8].
give
way
2.
give 1.
way
Flower
context
»symbol« »concept« »referent«
Fig. 3. Example for the uncertainty of symbols interpretation
Europe a give way sign is a well known symbol for a specific traffic rule, but
not for an aborigine from the deep Amazon’s jungle. It is uncertain, that he will
association the symbol with the same concept as we did (see Fig. 3). It is more
likely that he will associate it with a different set of essential characteristics
(e.g. red, long trunk) and will therefore refer to a different referent, e.g. flower.
Keeping in mind that symbols are a kind of communication tool, it is clear that
the issue of meaning relates to the receiver of the information, and not to the
transmitter [8]. In other words, in the case of choosing a symbol for a specific
concept, its meaning derives from how the user understands it, not from how it
was constructed [20]. To put this more forcefully: one can choose a symbol as
artfully or in as sophisticated a manner as possible; while this may facilitate the
interpretive process for the user [17], it cannot cause the user to understand (the
meaning of) the individual symbols, any more than someone can force another
to understand (the meaning) of what she or he is saying. It is like Friedrich
Nietzsche once said “there are no facts, only interpretations”[19].
4 Implication for Topic Maps and RDF
As we have seen in making a statement three factors are involved: symbol, con-
cept, referent. But what does this means for Topic Maps and RDF.
1. Topics and RDF resources represent concepts not referents
Topic and RDF resources clearly act as symbols for the representation of
subjects[12, 5, 7]. We have seen that the commonly used term “subject” is
not accurate enough in the context of meaning and interpretation [11]. The
term subject implies that a topic and RDF resource respectively represents
a referent. But as we have seen in discussing the semantic triangle this can
not be true, because the relation between a symbol and a referent is always
indirect [8, 16]. In fact topics as well as resources are representing concepts.
If we take a look at the modeling approach, we find evidence which supports
this thesis [21]. If an ontology designer needs to represent something, he has
to find a suitable symbol (topic or RDF resource). The subject identity is
defined by a URI and a corresponding definition (external or by the linked
subject indicator resource). In order to decide, if an available symbol (a)
is appropriate, he has to identify the characteristics (c) of the referent (r)
described in the symbols’ definition (r = ca ) and has to compare it with his
own interpretation on the object (r = cb ). Only if they are identical or at
least similar enough, the symbol is a suitable representation of the subject.
4
2. Multiple concepts represented by topics or RDF resources for every referent
This has considerable implications for RDF and Topic Maps. As we have
seen in section two, the concept creation for a referent depends on context
(time, place, opinion) [8] as well as on personal preferences and on previous
knowledge. Even, if its looks (based on equal URIs) that two ontology de-
signer model knowledge on the same referent, this does not necessary mean
that the symbol represent the same concept. Their individual set of essen-
tial characteristics can be different, e.g. a sub set of each other, a union or
even contradictorily. As a result the semantic web is not as consistent as we
might think. Instead of one symbol per subject [7, 3], it looks more like a
complex and evolving system of concepts, in terms of different interpreta-
tions [8, 22]. For a single referent multiple concepts exist and each of them
can be represented by a unique symbol, e.g. topic or RDF resource.
3. Definition of symbol identity via URI is inaccurate
This insight has implication on the way how subject identity of topics and
RDF resources respectively are defined. For example a Topic Maps created by
a car producer contains knowledge on price (URI: http://price). In addition
a customer could model his preferences on cars in a personal topic map,
e.g. max price (URI: http://price). As described in the use-case of Tim
Berners-Lee, suitable software agents could import these information from
both sources [1]. Based on the URI of the symbol an agent would come to
the conclusion that both models contain information on the same subject.
However, if we keep in mind that topic and RDF resources represent concepts
this can be problematic. Concepts are the sum of the individual essential
characteristics and these can be different [8, 17]. Producer as well as customer
talk about prices but may be from a different perspective, e.g. different types
of price like end user price, re-seller, minimum price etc. Because the relation
4
In analyzing Topic Maps we must not, that there is the option to explicit define,
that a topic represent a certain digital addressable resource via a subject locator [7].
This may look like the symbol represent a referent directly. However, even in this
case the topic act as a symbol representing a certain concept. The only difference is,
that the definition of the concept is commonly agreed and well-known. Thus what
the essential characteristics are, in term of the amount of digital data which can be
download from the defined URL.
between the referent and the symbol is only indirect, it is uncertain that two
symbols with the same URI represents the same referent.
As a results a software application could import or merge symbols with
identical URIs but it is uncertain if they represent the same concept. From
a problem-oriented view of the user the knowledge could be to low grained,
to detailed information, not relevant or even wrong. Using URI’s to identify
a topic or RDF resource is only suitable inside a closed domain, e.g. if a
controlled list of symbols is used. If the knowledge is made available to
applications other than those for which it was originally created [3], URIs
are not accurate enough.
4. Many incorrect ways to model a domain, but no single correct way
Many users got the impression that semantic modeling languages are more
precise than natural language. This is probably true to a certain extent,
because natural language is indeterminate resulting in an infinite amount
of possible expression of a concept [17], e.g. see the endless poems on love.
However, this is also true for semantic modeling. On one hand you have
different modeling languages, like Topic Maps, RDF, OWL etc, which can
be used to model the same statement but are not fully compatible amongst
each other [12]. On the other hand there are many incorrect ways to model a
domain, but no single correct way [21]. There are often modeling alternatives
and the best solution depends on the application. Modeling tends to be an
aesthetic activity rather than a technical construction.
For example, if someone wants to model the statement that the web resource
http://www.ilmenau.de contains relevant information on the German town
Ilmenau (see Fig. 4) he could model it as an external occurrence in Topic
Maps (variant 1), as a association in Topic Maps (variant 2) or as a RDF
triple (variant 3). The modeling approaches and used symbols may be dif-
ferent but the meaning is identical. A human may be able to understand
this. Using the common method for subject identity, software application
are limited by URIs and the structure of relations and get therefore the
wrong impression that these three statements are different. This makes the
exchange and integration of formally modeled knowledge of different sources
so difficult, because information can be incompatible or undetected although
the meaning is relevant for the recipient. In addition, semantic modeling is
a very dynamic and iterative process. During the modeling the designer get
a better and more detailed understanding of the domain and so it is often
necessary to revisit earlier decisions and modify some of them during the
modeling process [4, 21]. Therefore during time the same symbol evolves,
e.g. new names or associations are added or even removed. A fixed URI
cannot reflect these changes and is therefore not enough for identification of
changes over time.
In summary, to grasp the plurality of interpretations we can not represent
a subject as a single entity, but rather as a complex and evolving system of
different concepts depending on context, domain, origin or focused task. Each
concept is represented by formal symbols, e.g. topic or RDF resource. Instead
Ilmenau Ilmenau http://sample.ie/ilmenau
http://sample.ie/
contains »association«
relevant_info
relevant info
»RDF
web page triple«
ilmenau
»occurrence« »subject locator«
http://www-.ilmenau.de http://www-.ilmenau.de http://www-.ilmenau.de
Fig. 4. Modeling alternatives
of the traditionally promoted 1:1 relation between a subject and a symbol [7, 4],
it seems to look more like a cloud of multiple symbols representing individual
interpretation of a common referent Fig. 5.
»referent car«
status symbol
car
car
car
car
车 http://sample.ie/price
http://sample.ie/is_max
car car car
car
made of car http://sample.ie/car
htt
car p:/
/sa
mp
le.
ie/
is_
a
metal alloy steel
http://sample.ie/product
»custumer (topic map)« »producer map (rdf)«
Fig. 5. Concept cloud
5 Semantic Mapping
To realize the vision of the semantic web it is essential to exchange formally
modeled knowledge between applications and humans without loss of meaning
[3]. Fact is that a topic and RDF resource represent different concepts, thus
different sets of essential characteristics (c). In order to be able to integrate
knowledge on a relevant referent (r) from different sources (a,b),we need know
the available concepts (r - ca ,r - cb ) are related. Are they identical and if not
what needs to be done to adapt them in order to be able to integrate ca in
the semantic model of b. Such rules for transformation or adaption are called
semantic mappings [24]. For example think of an appointment software agent of
»referent height« »mapping«
height x 0,3 = http://sample.ie/height
height (foot in m)
http://sample.ie/height USA DE
»rule + meta-info«
ht
tp
:
//s
current
am
pl
e.
ie
/n
ee
de
d
snow http://sample.ie/skiing
»weather (topic map)« »personal preferences (rdf)«
Fig. 6. Subject cloud
a German tourist. If he goes to the USA the agent “knows” based on the modeled
personal references that the tourist likes to ski and that a certain height of snow
is needed for this activity. The agent could then exchange knowledge with a
weather information system, where the knowledge of the current snow height is
modeled, e.g. in a topic map. Combining both pieces of information allows the
agent to conclude, if the snow height is sufficient for a skiing appointment.
Obviously, the weather model as well as the preferences model must contain
a symbol representing the height of the snow (see Fig. 6). As we have seen
in the previous section the symbol are only indirect connected to the referent
“snow height” and in fact represent individual concept, which can be different,
e.g. the whether model represents height in foot and the preference model in
meters. In addition both model can uses different URIs or modeling languages to
identify the symbols, e.g. in the USA RDF and in Germany Topic Maps are used.
However, both models contain information more or less on the same referent. To
exchange and share the knowledge, it is necessary to create a semantic mapping,
which in this case defines a transformation rule for the conversion of foot in
meters and a linkage of the different URIs. These enable the agent to reuse the
modeled knowledge of the American information system without loss of meaning.
Such a conversion is a very simple mapping problem. But the same idea can be
applied to more complex tasks, too. If for example a semantic model uses a meta-
model and another one does not. Then a mapping rule can define how a relevant
sub graph of the first model can be extracted and transformed to be compatible
with the second model. Currently enormous efforts are made to formally model
knowledge in medicine, engineering and many other domains [2]. But in many
of these project different schemas, different symbols and modeling languages are
used. Only with efficient and flexible mapping a exchange of knowledge between
these different domains and source is possible without loss of meaning. However,
these semantic mappings are created for a specific purpose in term of bridging one
knowledge space with another. Mapping rules are only valid in a specific context,
e.g. time, place, creator or task and can change. As a result for two symbols
an endless amount of possible mappings can exist, similar to the plurality of
concepts - each for any user or field of application. In addition mappings can
contain complex transformation rules, and it is obviously not suitable to reinvent
them over and over again for similar tasks. Therefore reuse of mappings is a big
issue, but for this it is necessary to find existing suitable mappings and to know:
who, how and why these mapping were created.
6 Semantic Mapping Management System
To handle these multiple and complex semantic mappings in an efficient way and
to deal with the plurality of concepts, which is inherent to each semantic model,
a sophisticated management system for semantic mappings (MSM) is needed.
A first question for the design of such an MSM is, how to represent the symbols
or the fragments which need to be mapped. To enable a software application to
process them automatically, it may be suitable to represent the symbols using
a formal knowledge language. This language should be flexible and powerful
enough for the ubiquitous identification of the concepts as well as to deal with
linkage type mappings, complex mappings including the required mapping rules.
The second open question is how to represent the mapping rules, which
can involve all kinds of transformations, e.g. from simply mathematical func-
tion to complex transformation of sub graphs. The mapping should be flexible
and directly executable. For RDF the XSPARQL[27] language may be a good
candidate, because it combines the powerful query functionally of SPARQL[26]
with the transformation features of XQUERY. For Topic Maps such a sophisti-
cated query and transformation language is missing. However, XSPARQL may
be promising, but using a RDF or a Topic Maps specific language is not suit-
able. A mapping can require the transformation from one into another modeling
language (RDF in Topic Maps) or from quite different sources and therefore a
semantic language independent solution is needed.
Another relevant question for such a MSM is the identification of the symbols.
Inside the individual models, the symbols are identified by URIs. However, this is
not sufficient inside the semantic mapping, because symbols with identical URIS
from different origins can represent different concepts. As a result a distinction
beyond URIs is needed inside the MSM and therefore additional contextual
information must be added, e.g. creator, source, time, place etc. For a manual as
well as an automated processing and reuse of the mappings extensive meta data
on the mapping itself is required. In the end to be able to draw conclusion why
and how a certain mapping was created, may be the whole involved sub graph
of the original and targeted model is needed.
The process involved in creating and using context-based semantic mapping
is not sufficiently researched. Based on the presented argumentation at least the
following steps are relevant. They key question for a MSM is: how to support
the users in this process.
1. Analysis of the symbol or model fragments, which need to be integrated
or exchange. The objective of this phase is to identify the set of essential
characteristics of the concept represent by each symbol.
2. Search for existing semantic mapping, which describes how the set of essen-
tial characteristics of the source concept can be transformed into the set of
the target concept.
3. If no suitable semantic mapping exists, create a new one.
4. Document the semantic mapping, for searching and reuse. In particular im-
port are information on the creator, traceability, reasons for the mapping,
level of confidence as well as used matching algorithm.
In the creation process of semantic mappings different groups of users are in-
volved. For example human domain experts are needed, because they possess
the required back-ground knowledge of the domain and can interpret the con-
textual information. Only these experts are able to create a valid task or domain
specific mapping rule. In addition knowledge engineers are required to translate
this mapping rule in a formal knowledge representation, which can be processed
and executed. In general domain expert do not process the necessary experi-
ence in Topic Maps or RDF, therefore they need assistance. Suitable matching
algorithms (e.g. string or structure based) can be used to assists users in the
identification of possible mapping candidates. However, fully automatic deriva-
tion of mappings are not possible, yet [23]. Tools as well as algorithms are limited
to matching and can not create a creative cross-domain connection because the
necessary formal knowledge for an automated deduction is missing, which is the
reason for creating a mapping in the first place.
In addition individual software applications need to be able to flexible inte-
grate the functionality provided by an MSM system. For example the appoint-
ment agent in Tim Berners-Lee’s vision, needs to be able to send a request to the
MSM containing the source and the target symbol and receive a mapping. The
software architecture of such an MSM must consider these requirements, there-
fore a services-oriented architecture (SOA)[28] may be suitable. A SOA groups
functionality around business processes and packaged them as interoperable ser-
vices. By separating functions (search, creating, management, etc.) into distinct
services [28], they can be made accessible over the Internet in order to be flexible
combined and reused in any application needed [29].
7 Conclusions
In this paper we discuses question relating to meaning, interpretation and sub-
ject identity in modern semantic web languages like RDF and Topic Maps. Based
on the semiotic triangle we described the three factors involved whenever a state-
ment is made, or understood (symbol, concept, referent) and what implication
these have for Topic Maps and RDF. In particular topics as well as RDF re-
source are symbols representing concepts and not referents as the common term
subject would indicate. Based on this insight, we explained how the resulting
plurality and uncertainness of the interpretation of symbols can be handled using
semantic mappings. Concluding we define recommendations and design guide-
lines for a semantic mapping management system, which is needed to support
users and application in creating, reusing, managing and applying these semantic
mappings.
We could show the necessity for the support of semantic mapping but many
detail questions are still not solved sufficiently , e.g. how semantic mappings
can be represented, how and which meta knowledge on semantic mapping is
needed as well as how the process of mapping is conducted and how can it be
supported. Overall, we came to the conclusion that the remarkable efforts made
in formally annotation the World Wide Web are just the first step. In a second
the creation of semantic mappings is essential to achieve the goals of “global
knowledge federation”[22, 30] and even to begin to enable the aggregation of
information and knowledge by humans and software agents on a scale large
enough to control the overall informationglut[11].
References
1. Berners-Lee, T., Hendler, J., Lassila, O.: The Semantic Web - A new form of Web
content that is meaningful to computers will unleash a revolution of new possibilities,
Scientific American Magazine, http://www.sciam.com/article.cfm?id=the-semantic-
webUNDprint=true, 2001.
2. Antoniou, G. and Harmelen, F.: A Semantic Web Primer (Cooperative Information
Systems),The MIT Press, 2004.
3. Manola, F. and Miller, E.(eds.): RDF Primer, http://www.w3.org/TR/REC-rdf-
syntax/, 2004.
4. Pepper, S.: The TAO of Topic Maps - Finding the Way in the Age of Infoglut,
http://www.ontopia.net/topicmaps/materials/tao.html, Norway, 2002.
5. Beckett, D.(eds.): RDF/XML Syntax Specification (Revised),
http://www.w3.org/TR/rdf-syntax-grammar/, 2004.
6. McGuinness, D. L. and Harmelen, F. van (eds.): OWL Web Ontology Language -
Overview, http://www.w3.org/TR/owl-features/, 2004.
7. Garshol, L. M. and Moore, G.: ISO/IEC JTC1/SC34, Informa-
tion Technology – Document Description and Processing Languages,
http://www.isotopicmaps.org/sam/ sam-model/, 2006.
8. Miller, T. and Thomas H., ”Indices, Meaning and Topic Maps: Some Observations”,
in: L. Maicher, A. Siegel and L. M. Garshol, Leveraging the Semantics of Topic Maps
– Second International Conference on Topic Map Research and Applications, TMRA
2006, Leipzig, Germany, October 11-12, 2006, Berlin: Springer, 2007, 130–139.
9. Sigel, A.: ”Topic Maps in Knowledge Organization”, in J.Park (ed.) and S.Hunting
(tech. ed.): XML Topic Maps: Creating and Using Topic Maps for the Web. Pearson
Education, 2002, 383-476.
10. Fugmann, R.: Subject Analysis and Indexing: Theoretical Foundation and Practical
Advice. Frankfurt a.M.: Indeks, 1993.
11. Pepper, S. and Schwab, S.: Curing the Web’s Identity Crisis – Subject Indicators
for RDF. http://www.ontopia.net/topicmaps/materials/identitycrisis.html, 2003.
12. Garshol, L. M.: Living with topic maps and RDF – Topic maps, RDF, DAML, OIL,
OWL, TMCL, Ontopia, http://www.ontopia.net/topicmaps/materials/tmrdf.html,
2004.
13. Tauberer, J.: What Is RDF, http://www.xml.com/pub/a/2001/01/24/rdf.html?
page=1, 2006.
14. Garshol, L.M. et al (eds.): RDFTM: Survey of Interoperability Proposals.
http://tesi.fabio.web.cs.unibo.it/RDFTM/DraftSurvey, 2005.
15. Hayes, P.: RDF Semantics, http://www.w3.org/TR/rdf-mt/, 2004
16. Ogden, C.K. and I.A.Richards: The Meaning of Meaning.Harcourt, 1967.
17. Fugmann, R.: The Five-Axiom Theory of Indexing and Information Supply. Journal
of the American Society for Information Science Vol. 36 (2), 1985, 116-129.
18. Heidegger, M.: Sein und Zeit, 16th. ed. Tübingen: Max Niemeyer, 1986.
19. Eco, U.: Kant and the platypus, essay on language and cognition,New York: Har-
cout Brace, 1997.
20. Peterson, E.: ”Beneath the Metadata – Some Philosophical Problems with
Folksonomy”, in: D-Lib Magazine, 12(11), http://www.dlib.org/dlib/ novem-
ber06/peterson/11peterson.html, 2006.
21. Garshol, L. M.: ”Towards a Methotology for Developing Topic Maps Ontologies”,
in Maicher, L, Siegel, A, Garshol, L. M. (eds.): Leveraging the Semantics of Topic
Maps – Second International Conference on Topic Map Research and Applications,
TMRA 2006, Leipzig, Germany, October 11-12, 2006, Berlin Heidelberg New York,
Springer, 2007, 20–31.
22. Karabeg, D.: What is knowledge federation?,
http://heim.ifi.uio.no/ dino/KF/KF.pdf, 2008.
23. Noy, N.: Semantic Integration: A Survey of Ontology-Based Approaches,Special
Issue on Semantic Integration, SIGMOD Record, Volume 33, Issue 4, 2004, 65-70
24. Conroy, C., O’Sullivan, D., Lewis, D.: A tagging approach to ontology mapping,
Ontology Matching Workshop, International Semantic Web Conference (ISWC 2007),
Busan, Korea, 11th November, CEUR-WS, 2007.
25. Sasson, R. and Gaur A.: Signs, Symbols and Icons,Intellect Books, Exeter, England,
1991, 191
26. Prud, E. and Seaborne A. (eds.): SPARQL Query Language for RDF,
http://www.w3.org/TR/rdf-sparql-query/, 2008.
27. W. Akhtar, J. Kopecky, T. Krennwallner, A. Polleres: XSPARQL: traveling betwen
the xml and rdf worlds - and avoidings the XSLT pilgrimage, technical report, deri
technical report, 2007.
28. M. Bell: Service-Oriented Modeling: Service Analysis, Design, and Architecture,
Wiley and Sons, 2008.
29. Aier, S. and Schnherr M.(eds.): Enterprise Application Integration. Serviceorien-
tierung und nachhaltige Architekturen 2. ed., Gito, Berlin, 2006.
30. Karabeg, D.: KNOWLEDGE FEDERATION WIKI,
http://knowledgefederation.org/What is knowledge federation, 2008.
31. Eco, U.: Einfhrung in die Semiotik, UTB, Stuttgart, 2002.