=Paper= {{Paper |id=Vol-294/paper-4 |storemode=property |title=Some Considerations on Openness of Design Information |pdfUrl=https://ceur-ws.org/Vol-294/paper04.pdf |volume=Vol-294 |authors=Hideaki Takeda |dblpUrl=https://dblp.org/rec/conf/semweb/Takeda07 }} ==Some Considerations on Openness of Design Information== https://ceur-ws.org/Vol-294/paper04.pdf
    Some considerations on openness of design information
                     (Position Paper)

                                        Hideaki Takeda

                             National Institute of Informatics (NII)
       Research into Artifacts, Center for Engineering (RACE), The University of Tokyo
                                        takeda@nii.ac.jp



       Abstract. Towards a sustainable society, design of artifacts must be optimized
       with limited resources on the earth while keeping our life. In order to realize it,
       I emphasize openness of design information. In this paper, I discuss needs for
       openness of design information and methods to realize it. I argue why design
       information should be open and what benefits will result by opening and
       sharing design information. Opening design information looks difficult
       considering the current structure of the industries, but I show some possibilities
       from two aspects of design activities. In software design, open source software
       is getting accepted as a way of developing software products. I overview it and
       analyze how it can be applied to artifact design. Then I discuss how such an
       environment can be built. Identification, representation, and sharing mechanism
       are crucial. Lastly I summarize discussion with people in the design
       community. Many people disagree with opening design information, but I
       dispute with their objections.




1    Introduction

Design has been one of most important human activities which has pushed forward
our civilization. It is no doubt that science and technology has provided the basis of
our civilization. But realization of civilization is not the role of science or technology,
rather design. Piles of design activities based on science and technology have really
shaped our civilization. As a result, our environment is fulfilled with a very wide
variety of designed artifacts to make our life happy.
   But now a new demand for design arises. Our design capability is tested by the
global environment problems, i.e., we are requested to achieve optimal solutions by
design artifacts with limited resources on the earth. Since we are struggling to
maintain such a variety of artifacts even now, the new demand is challenging to
design community.
   The crucial point is that most design activities have been hidden. To realize
sustainable society, we wish to optimize our environment with artifacts. But there are
no ways to do it because almost all design activities are performed independently and
separately. The hiddenness of design is the major hurdle to prevent it.
   Why are design activities hidden in general? There are two primitive reasons. One
is overlook of the importance of design activities. Design activities are so daily and so
2   Hideaki Takeda


common that it is difficult to understand the importance. The other reason is
anonymity, i.e., design activities are performed by a lot of anonymous designers.
They don’t think that their activities are valuable for other people except their
company and disciples. Anyway our society is built and maintained under the
principle that design activities are hidden. Companies engaged to design have done
their business with this principle.
   Now we have a chance to change the system thanks to rapid development of digital
technologies. We are now tools easily to share information in spite of time, space, and
organization. So I argue openness of design information which can overcome
hiddenness of design in this paper.
   I discuss needs for openness of design information and methods to realize it. I
argue why design information should be open and what benefits will result by
opening and sharing design information. Then I discuss how such an environment can
be built. Identification, representation, and sharing mechanism are crucial. Lastly I
summarize discussion with people in the design community. Many people disagree
with opening design information, but I dispute with their objections.


2    Definition of Openness of Design Information

In this section, I define openness of design information in general.
   First I define design information. Here design information on a product means all
kind of information that is used to realize it as an artifact. It includes not only
information that the product itself has but also provenance of the product.

1. Inherent information: information that the product itself has. It includes design
   specifications which show performance and basic attributes of the product, 2D or
   3D drawings which represent structure, shape, and materials. It can be obtained
   approximately by the third party with analysis of the product itself.
2. Provenance information: information that indicates the process of realization of
   the product, i.e., how the product is suggested, how it is articulated, and how it is
   gotten its details. It includes required specifications, design rationale, used
   knowledge, and design process including decision makings. It is no way to know
   this kind of information except designers that design it.

The former is relatively easy to imagine but it alone is insufficient as design
information because designed artifacts are meaningful when we know how designers
intend and how the intention is articulated.
   In addition to design information, we also need manufacturing information on a
product. It is another kind of provenance information, i.e., how it is materially
realized. It includes information on tools and machines that are used and
manufacturing process that is actually done. It is equally important information to
design information, but I discuss design information in this paper to focus on design
issues.
   Then I refer to openness. Openness of information here means that information is
publicly available. It doesn’t care where information is located or who owns, but it is
                                    Some considerations on openness of design information
                                                                    (Position Paper) 3

important that information is permanently available. World Wide Web (WWW, Web)
is a good practice of openness of information because information on Web is basically
publicly and permanently available.


3     Reasons and Benefits for Opening of Design Information

The ultimate reason to realize openness of design information is sharing of
intellectual work by human being. Design is one of the most important intellectual
activities by human being. It is not exclusive like artistic activity but ubiquitously
exists in our society. We have spent a huge amount of effort on designing artifacts for
a long time. But the effort is basically isolated, i.e., very locally collaborated and
inherited. We can learn how to write novels by reading novels more or less. But
designed artifacts, in particular modern industrial artifacts are by far harder to learn
how we can design from. They are mostly like a black box, i.e., understanding
artifacts is difficult because of its complexity and understanding of design intention is
by far difficult because of implicit nature. It is nature of design that every effort on
design is embedded as a physical artifact, so it has been reasonable until now. But the
situation is changed. One is that most of design process is digitized. We can preserve
all information on design in computers. The other is that we have the way to distribute
information, i.e., Internet and World Wide Web. So we have opportunity to enhance
sharing of design activities.
    The above is the ideal goal, but there are many benefits to enable openness of
design information. I here picked up six benefits as follows;

1.   Benefits for customers:
     Customers of products can know more information about products. It is useful for
     them to decide which products they buy. They can understand designers’
     intention and compare it with their purpose of purchase. It is also useful to
     increase creditability for products. It is analogous to food safety. People prefer
     not only food without toxic or other problematic ingredient but also food of
     which production process is clear and reliable. In designed products, it
     corresponds to inherent design information and provenance design information
     respectively. It is becoming right for customers to know such information on
     products.
2.   Benefits for designers:
     It is clear that sharing design information will increase productivity of design.
     Products are rarely created from scratch. Rather products are created as
     improvement of existing products or use them as reference. It takes a lot of time
     to understand such existing products, namely reverse engineering. If design
     information is open already, designers can start their new design from the top of
     existing design. It will sometimes result in reduction of costs and sometimes
     result in faster evolution of products. Another benefit is to enhance more
     collaboration among designers. One designer may add extra ideas in addition to
     ideas by the other designer if they could understand their design processes to
4    Hideaki Takeda


     each other. They will be able to collaborate to each other by integrating their
     ideas.
3.   Benefits for both designers and customers
     Opening of design information makes a new opportunity for collaboration
     between designers and customers. As mentioned in the above, customers can
     share understanding of designed artifacts with designers. Some advanced
     customers can make feedback to designers to improve the products, or
     furthermore they may join design. Such a process will result in more suitable
     design to customers’ needs. It is also expected that it will reduce mistakes in
     design. It is valuable for both designers and customers.
4.   Benefits for product life cycle
     We are now conscious that product life cycle includes not just design,
     manufacturing and use but maintenance, recycle, and disposal [1]. The whole
     product life is basically governed by design because other processes are
     dependent on products already produced according to design. Opening design
     information can smoothen these processes, e.g., it reduces analysis for
     disassembly and recycle.
5.   Benefits for society – preservation of knowledge –
     Designed products are results of our intellectual work. We spend a lot of time to
     design various artifacts. We’ve produced tremendous artifacts but most of them
     have been disappeared according to change of our society and often market.
     Preserving all physical artifacts is impossible, but preserving information on
     them is possible. By preserving artifacts as information is our heritage for future
     generation.
6.   Benefits for society – design as commons –
     The computer technology created a new environment where people easily operate
     and distribute information. It doesn’t simply mean that information becomes
     public. Rather information can be controlled more intentionally. Now there is
     danger for digital divide between developed and developing countries.
     Information commons is needed [2]. Design should be also commons. Sharing
     design information between developed and developing counties can help to
     improve quality of life in developing countries by designing and manufacturing
     products by themselves

In above six types of benefits, the first three are directly related to the current product
markets, while the rest are indirectly but the impact to the society is larger. Of course,
there can be demerits. We will discuss them in Section 7.


4     Considerations for Adaptability to Industries

Before going on methods for openness of design information, I discuss whether
openness of design information is acceptable depending on types of industries in two
ways. One is typology by product architecture and the other is by technology
developing phases.
                                    Some considerations on openness of design information
                                                                    (Position Paper) 5

4. 1   Integral architecture and modular architecture

Function is the purpose of design and attribute is means to realize function. Generally
speaking, design is mapping from function to attribute [3]. Since functions required
for modern industrial products are sophisticated, attributes of products are
complicated. They usually consist of some amount of components. So composition of
components is a common feature of modern industrial products, rather the way of
composition is often more important than components themselves. Ulrich pointed out
that there are mainly two types of component composition in modern industrial
products [4]. He called it “product architecture”. One is “integral architecture” which
means functions and structures are complicatedly interdependent. It takes a lot of
efforts to integrate components. It is done by human communication. But the tuning
of overall performance is relatively easy. The typical example is automobile.
   The other is “modular architecture” which means functions and structures are well
correspondent to each other. Since interfaces for components are predefined,
composition of components is easy. On the other hand tuning of performance is not
easy. The typical example is personal computer.
   Product architecture is not solely related to products themselves but it is said that it
is also related to organization culture which varies from country to country [5].
Companies in countries like USA often show strength in products in modular
architecture, on the other hand, those in Japan in integral architecture.
   Design information in modular architecture is easy to shift open, since openness of
interface is already done. Standardization lies in the same line. So we don’t worry
about openness of design information on this type of products so much. Sooner or
later, at least inherent information becomes open. But concerning provenance
information, we need another system to push towards openness.
   Design information in integral architecture looks difficult to open. But the effect
seems larger, i.e., openness of design information can compensate the current
difficulty in design process. When designers of components integrate their
components, a lot of time is consumed by understanding design to each other.
Explication of not only inherent information but also provenance information can help
such understanding. Software design is exactly this case, and it looks successful as we
will see in the next session.


4.2    Pre-competitive, Competitive, and post-competitive products

Yoshikawa addressed that there are three different phases in technology development,
namely pre-competitive, competitive, and pos-competitive phases [6]. Pre-
competitive phase means that technology is not matured to complete so that
stakeholders like academia and industries are easy to cooperate. Competitive phase
means that technology is well established but still under development so that
competition in the market occurs. Post-competitive phase means that technology is
already matured and no more development is expected so that little competition
occurs.
   If products are now in competitive phase, it is difficult to impose openness of
design information.
6     Hideaki Takeda


   If products are in post-competitive phase, companies may welcome openness of
design information because in this phase companies are often continuing production
not for benefits but for social duty. In this case, enforcement by laws and social
consensus can work well.
   If products are in pre-competitive phase, stakeholders naturally exchange
information to improve technology.


5      Lessons Learnt from Practices

I overview design practices in the open source culture in this section. Open source
design is originated in software design, and it becomes a movement or a culture. It is
now spreading out other product design slowly but steadily.


5.1    Open source software

We can learn from the recent movement in software engineering so-called “Open
source” software. Open source software means that codes of software products are
open and can be re-used. By opening codes, programmers can develop their own
software products by re-using or modifying existing open source software products.
The most typical example is Linux, but there are more products like Firefox and
Apache. Another example is Wikipedia which is not a software product but a huge
knowledge base contributed by a lot of people who are mostly anonymous.
Open source movement changes the software development process. A new
development process is called “bazaar” style in contract to “cathedral” style [7]. In the
bazaar style, software products are open from the early stage so that everyone can
contribute the development. Frequent release policy is also included in the list of Web
2.0 features [8]. It is said that it contributes to improve software quality and users’
satisfactions.
    Once open software movement was regarded as the enemy of software industry. It
seemed that they claimed invalidity of business of software industry. But people
realized that anyway the bazaar style could produce nice software products recently.
So many software companies are now collaborative to the open software community.
    We can learn many lessons from success in software engineering. Firstly sharing
design information can reduce design costs with keeping quality. If we could re-use
existing design solutions, we can focus on more creative part of design. It already
happens that design information is shared in a company. If we could extend it to
community-wide sharing, more effects on cost and quality would be expected.
    Secondly design information could be preserved. In open source software, even if
the original developer of a software product looses interest on it and stop developing
it, other people can succeed to develop it if they like. So software can survive. In
engineering design, death of companies implies death of design information. There
are no ways to access information on products of which manufacturer closed its
business. If design information is already opened, information can be accessible
whichever manufacturer is alive or not.
                                    Some considerations on openness of design information
                                                                    (Position Paper) 7

5.2   Artifact design in the open source culture

As we mentioned, there are many successful projects on software products. There are
already some projects that actually run open design activities even for non-software
products. Most of them are products related to computers. It is called open source
hardware [9]. For example Opencores.org [10] is developing microprocessors and
other chips with open source style [11]. They are mainly inspired by success of open
source software and also technically related to open source software.
   There are some exceptions. ThinkCycle, a spinout of MIT student project, offers an
environment for open collaborative design [12][13]. The aim of the project is sharing
of design knowledge, in particular design for products needed socially. The project
offers a collaborative environment where domain experts and designers discuss and
show design solutions. The results are archived as documents. A typical design case
with this project is design of a novel low-cost IV drip flow for patients infected with
cholera. There are more than 200 documents and many design results in the site.
   There are also other projects like “The Open Prosthetics Project” [14] in which
designers share knowledge about prosthetics design.
   The main focus on these projects is how to provide collaborative environments
among people who work in different domains and spread out geographically. Thanks
to recent development of the Internet technologies, it is not so difficult to provide
them. The tackling problem is a social one, i.e., how to involve and encourage people
or develop a culture for sharing. If there arises such a culture in a project, it will
continue. Otherwise it will disappear even if there is a good computer environment
for collaboration.
   The other problem is representation. In open source software projects, information
on design is represented as software products themselves (source codes),
documentation, and discussion archives like mailing-list logs. The significant feature
of software in comparison to artifact design, source codes basically contain all
information on software products. Designers can understand design of software
products by reading source codes. In artifact design, it is different. In the projects on
artifacts, information is shared as documents written with texts and drawing. It just
contains partial and ambiguous information about design.
   In artifact design, it is different. In the projects on artifacts, information is shared
as documents written with texts and drawing. It just contains partial and ambiguous
information about design.
   It is not a serious problem when the amount of information is relatively small.
People may compensate information by communicating to each other. But if it
becomes large enough, it would be troublesome and maybe obstacle for information
sharing. We need formal representation for design information sharing in a large
scale.
8      Hideaki Takeda


6       Methods to Realize Openness of Design Information

As we mentioned, we need a formal system for sharing design information. Opening
and sharing design information on artifacts needs some new technologies. I pick up
three issues here, i.e., identification, representation, and sharing mechanism.


6. 1 Identification

In order to distribute design information on artifacts, artifacts and design information
should have identification, and then they should be associated to each other. Each
design should have its own identification. In the Internet, it can be achieved by URI
(Uniform Resource Identifier) [15]. URI is generalization of URL (Uniform Resource
Locator) and can work not only as address of web pages but also as identification of
any objects. Any URI is unique in the Internet. But URI itself is not sufficient because
it cannot carry any information about relationship among objects. In Semantic Web
[16], it is realized as RDF/S (Resource Description Framework/RDF Schema)[17][18]
and OWL (Web Ontology Language)[19]. A RDF statement is a triple among URIs
and represents a relation between a resource to another with a label (property). RDFS
offers modeling mechanism for RDF statements like class hierarchy. OWL offers
more powerful modeling mechanism than RDFS. By using these languages, we can
represent not only relationship among design but also contents of design.
   In mass production, many products are produced from a single design model. It is
analogous to class-instance relation in object-oriented programming paradigm. Mass
products usually have manufacturer’s serial number that is unique in a company or
product. Serial numbers can easily be converted into URN (Uniform Resource Name),
which is another subset of URI. It can be associated to class representation by RDF/S
or OWL. But association mechanism is needed. Association can be realized by
resolution servers such as DNS (Domain Name System) in networking and DOI
(Digital Object Identifier) [20] in digital libraries.


6. 2    Representation

The second problem is how to represent design information. I categorized design
information into two types of information, i.e., inherent information and provenance
information
   There are many efforts how to represent design objects such as 3D CAD and
product modeling, which is what I mentioned as inherent information. But it is not
sufficient because they are just representation of the final product. We need to
represent information on the other stage like conceptual design. That is what I called
provenance information.
   Concepts in design should be represented in a formal way. It is the role of ontology
for design [21] [22], and Semantic Web enables to publish representation with
concepts in ontology in the Internet.
   Furthermore we need information on design process, i.e., how designers proceed
their design. It is a more serious problem because there are no general agreements
                                    Some considerations on openness of design information
                                                                    (Position Paper) 9

how design process should be represented. I here show an attempt to publish design
process information. In [23], we represent design knowledge related to design process
with XML syntax. A design document consists of two parts. One is a human-readable
part in which a normal text is included. The other is a logical part in which knowledge
on design is described in a logical form. Knowledge is described with concepts in
predicate ontology, attribute ontology, and object ontology. We model design process
by abduction [24] and represent design process as application of design knowledge in
abductive inference. Then we can know design rationale for each design by tracing
design knowledge, i.e., why it is designed in such a way. It is merely a proposal how
design knowledge and design process can be represented, but we need to discuss it
seriously to make design process more transparent.


6.3    Sharing mechanism

Another problem is sharing mechanism, i.e., how information is actually distributed
and shared. As I mentioned, it is important how to involve and encourage people in
community of sharing information.
  We can learn from recent development of information technology such as blogging
and social networking services.


6.4   An Image of Realization

The Internet technologies provide a good basis to realize openness of design
information.    But design information differs mainly in two ways. One is
complicatedness of information. Design information is more complicated not only for
in structure which comes from physical structure such as CAD data but also in
structure which comes from different aspects or design stages such as requirement,
concept design, detail design. It is a difficult problem but relatively easy because it is
purely a problem of information technology.
10    Hideaki Takeda


   The other is duality of physical entity and information entity. An artifact has now
two entities. One is a physical entity which is manufactured, distributed, used and
defeated. The other is an information entity which is created and evolved through
designing, manufacturing, distributing, using, and defeat. Two entities should be
coupled. Some technologies such as RFID tags and 3D bar-codes can help its
realization, but it is still difficult and to be solved in the future.
   Figure 1 is an image of sharing of design information. From the viewpoint of the
information world, artifacts would become a kind of information which is operational
in the world. From the viewpoint of the physical world, artifacts would be equipped
with computers which can carry information and acquiring new information through
the physical environment.




Fig. 1. An image of sharing of design information: each artifact with an own URI is distributed
and used in the physical world. Information on design such as rationale, specification, process
and knowledge and information through usage which is identified with the URL is retrieved
and updated via the Internet.




7     Discussion

I already talked this idea on a symposium in a design community in Japan. Many
participants, in particular designers in companies, disagree with opening design
information. I summarize their objections and my answers to them.

[Question]
   Secret of design cannot be opened. It is core competence of companies.
[Answer]
   Competitive design can be excluded. Even accepting this exception, there is a lot
   of useful design information for others.
                                      Some considerations on openness of design information
                                                                     (Position Paper) 11

[Question]
   Design information is not understandable for others. For example, design
   information is usually valuable with the manufacturing knowledge. So it is useless
   to open design information.
[Answer]
   I agree that design information is not completely understandable for others. But
   even partial understanding is valuable. If it would be true, it implies that opening
   design information would not make direct dangers for companies because other
   companies cannot produce copy products easily even if such information is
   available.
[Question]
   Exhibit of design information increases danger for product-liability lawsuits.
   Companies should control information carefully not to crease this kind of risk.
[Answer]
   I think that it is opposite. Information hiding may cause a lot of cost, e.g., if
   serious accidents with products would happen. Opening design information in
   advance can reduce such risk.
[Question]
   There are no reasons to bear such cost.
[Answer]
   Opening design information is beneficial for companies.
      - Wise consumers trust companies that open their information more than those
       that do not.
      - Opening design information will reduce future costs to maintain products.
       Products may be maintained by other parties with such information.


7 SUMMARY

In this paper, I discuss the value of openness of design information. I admit that
discussion here is rough and not comprehensive at all. What I intended is to invoke
open discussion for this issue. Design information is valuable but it is not solely
valuable for companies it is valuable for society. I believe that openness of design
information is crucial for design community just to adopt the Internet era but to
unlock the future of design for the welfare of mankind.


REFERENCES

[1] Asedu Y and Gu P. Product life cycle cost analysis: state of the art review. International
   Journal of Production Research, 1998, 36(4), 883 - 908 (Taylor & Francis)
[2] Iwata S. and Chen R.S. Editorial: Science and the Digital Divide, Science 21 October 2005,
   310(5747), p. 405.
[3] Yoshikawa H. General design theory and a CAD system. Man-Machine Communication in
   CAD/CAM, Proceedings of the IFIP Working Group 5.2 Working Conference 1980
   (Tokyo), Sata T. and Warman E.A. (eds.), pp. 35-58, 1981 (North-Holland).
12    Hideaki Takeda

[4] Ulrich, K. The role of product architecture in the manufacturing firm, Research Policy, 24,
   1995, 419-440.
[5] Fujimoto T. Architecture-based Comparative Advantage in Japan and Asia. MMRC
   Discussion Paper No. 94, 21COE, University of Tokyo, 2006.
[6] Yoshikawa, H. Intelligent Manufacturing Systems: Technical Co-operation that Transcends
   Cultural Differences. In Yoshikawa H. and Goossenaerts J., eds. Information Infrastructure
   Systems for Manufacturing, IFIP Transaction B-14, 1994 (Elsevier North Holland,
   Amsterdam)
[7] Raymond E.S. The Cathedral and the Bazaar: Musings on Linux and Open Source by an
   Accidental Revolutionary. 2001, O'Reilly & Associates
[8] O'Reilly T. What Is Web 2.0 Design Patterns and Business Models for the Next Generation
   of Software. 2005, http://www.oreillynet.com/pub/a/oreilly/tim/news/2005/09/30/what-is-
   web-20.html (Last Visited: September 26, 2007)
[9] Open Source Hardware, Wikipedia. http://en.wikipedia.org/wiki/Open_hardware (Last
   Visited: September 26, 2007)
[10] Opencores.org http://www.opencores.org/ (Last Visited: September 26, 2007)
[11] Open Source Takes on Hardware Biz, Wired News, Dec, 17, 2003
   http://www.wired.com/news/business/0,1367,61631,00.html (Last Visited: September 26,
   2007)
[12] Sawhney N. et al. ThinkCycle: Sharing Distributed Design Knowledge for Open
   Collaborative Design. Int’l J. of Technologies for the Advancement of Knowledge and
   Learning (TechKnowLogia), 4(1), 2002
[13] ThinkCycle http://www.thinkcycle.org/ (Not available at September 26, 2007)
[14] The Open Prosthetics Project, http://openprosthetics.org/ (Last Visited: September 26,
   2007)
[15] Berners-Lee T., Fielding R., and Masinter L. Uniform Resource Identifier (URI): Generic
   Syntax. Request for Comments: 3986, IETF, January 2005. http://tools.ietf.org/html/rfc3986
   (Last Visited: September 26, 2007)
[16] Berners-Lee T., Handler J., and Lassila O. The Semantic Web. Scientific American, May
   2001.
[17] Manola F. and Miller E. RDF Primer. W3C Recommendation, 10 February 2004,
   http://www.w3.org/TR/rdf-primer/ (Last Visited: September 26, 2007)
[18] Brickley D. and Guha R.V. RDF Vocabulary Description Language 1.0: RDF Schema.
   W3C Recommendation, 10 February 2004, http://www.w3.org/TR/rdf-schema/ (Last
   Visited: September 26, 2007)
[19] McGuinness D. L. and van Harmelen F. OWL Web Ontology Language Overview. W3C
   Recommendation, 10 February 2004, http://www.w3.org/TR/owl-features (Last Visited:
   September 26, 2007)
[20] International DOI Foundation, http://www.doi.org/ (Last Visited: September 26, 2007)
[21] Yoshioka M., Umeda Y., Takeda H., Shimomura Y., Nomaguchi Y. and Tomiyama T.
   Physical concept ontology for the knowledge intensive engineering framework. Advanced
   Engineering Informatics, 2004, 18(2), pp. 95–113.
[22] Kitamura Y., Kashiwase M., Fuse M. and Mizoguchi R. Deployment of an ontological
   framework of functional design knowledge, Advanced Engineering Informatics, 2004, 18(2)
   pp. 115-127.
[23] Takeda H., Yoshioka M., Shimomura Y., Fujimoto Y., Morimoto K. and Oniki W. An
   Architecture for Designers' Support Systems with Knowledge-embedded Documents. In The
   Fifteenth International Conference on Engineering Design (ICED 05), Melbourne, 2005.
[24] Takeda, H. Abduction for design. In Gero, J., Sudweeks, F., eds.: Proceedings of the IFIP
   WG5.2 International Workshop on Formal Design Method for CAD, Tallinn, 1993 (Elsevier
   Science Publishers B.V.)