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Understanding dependable computing concepts

Ubiquity, Volume 2007 Issue November | BY Goutam Kumar Saha 


Full citation in the ACM Digital Library

This work aims to visually describe the important concepts of a dependable computing system and the relationships between the concepts. The concept map here for dependable computing system concepts would help us for easier and meaningful understanding of this emerging important research topic of computer science and engineering. Readers here won't feel tired of reading long text horizontally lines after lines for conceptualizing this much research and interesting topic.


The term Dependability is defined as the trustworthiness of a computing system that allows reliance to be justifiably placed on the service it delivers. Dependability for a computing system has the following important attributes: (a) Availability (i.e., readiness for correct service), (b) Reliability (i.e., continuity of correct service), (c) Safety (i.e., absence of catastrophic consequences on the users and environment), (d) Security (the concurrent existence of confidentiality and integrity), and (e) Maintainability (probability that a system will be retained in or restored to a specified condition within a given period of time). The more about dependable computing has been graphically described in the concept map as shown in figure-1. The Concept Map (CMAP) for Dependable Computing System here has been developed by using the IHMC Cmap Tools. This is a very useful tool for organizing and representing knowledge as the structured ones and for navigating also among various concept maps. CMAP is also useful for summarization or abstraction of topics. Fundamental concepts of Dependable Computing and their relationships have been graphically represented in the self-describing concept map (figure-1). This article aims to cover dependable computing concepts in a single one-page figure only.

Concept Mapping for Dependable Computing Knowledge Representation:

Concepts are the generalization of knowledge of ideas conveyed in some forms for example, books, documents, speeches or lectures. Concept is nothing but a perceived regularity in events or objects. Propositions state how concepts are linked together. A Concept Map comprises of concepts and propositions. Concept Maps are the graphical representations of knowledge that are comprised of concepts and the relationships among them. Concept maps are 2-dimensional representations of cognitive structures showing the hierarchies and interconnections of concepts involved in a discipline or a sub-discipline. This is an important tool for developing our both sensing and intuitive skills. Sensing skill is important to focus on already known and new information, whereas intuition skill helps us to construct relationships. It is to organize the information by groups. In a concept map, the nodes (in circles or rectangles) have been used to enclose the key concepts and these nodes have been linked with lines (normally directed downward) and words (e.g., verbs, preposition etc.,) that describe the connection.

Professor Joseph Novak developed concept maps that represent organized knowledge. A domain expert has hierarchically structured knowledge. Organized knowledge is comprised of concepts and propositions that are hierarchically structured in cognitive structure to aid creativity that begins with infants. Creativity is must to see interrelationships between various map segments. We need context dependent organized knowledge for effective teaching and effective learning and for answering focus questions. Creativity only can produce a very high level of meaningful statement. Concept is the highest level of "abstraction" for the map but it is the lower level of abstraction in the ontology.

A concept map has the following characteristics: -

(a) A hierarchical concept map contains the most general concept at the top and the most specific one at the bottom,
(b) Cross links are to link different map segments,
(c) Examples are to clarify the meaning of a concept.

In order to construct a concept map we must have familiarity with the general topic as well as an in-depth knowledge on a specific topic such as on dependable computing system here.

Concept Mapping Guidelines:

While developing Concept Maps, we may follow the following guidelines in order to develop a good concept map:

(a) To note the major concepts,
(b) To note more specific concepts for each major concepts for grouping related ideas,
(c) To inter link the major ideas,
(d) To write linking words,
(e) To do cross-linking between map segments (arrowhead for upward linking), and
(f) To label these lines with linking words or phrases to form meaningful statements.


Dependable Computing concepts and their relations have been described lucidly by this Concept Map. More specific concepts about dependability could be described in details by other concept maps and those could be integrated for navigating between them through hyperlinks. Concept maps are very useful as a means for representing the emerging science knowledge and for increasing meaningful learning in sciences in contrast to simply memorizing the text. Representing the expert knowledge of individuals or of teams in research, government, business and in education becomes easier by this useful concept mapping tool. It is to stimulate our idea generation and creativity. It is definitely carving out a strong position for brainstorming, complex ideas communication, and formal argument representation. Formalized concept maps are being used in software design or in UML. It is a first step in ontology building.

Further Reading:

[1] A. Avizienis, J.C. Laprie, B. Randell, "Fundamental Concepts of Dependability," Research Report No. 1145, LAAS-CNRS, 2001.
[2] K. Rajaraman, A. Tan, "Knowledge Discovery from Texts: A Concept Frame Graph Approach," Proceedings of the Conference on Information & Knowledge Management, 2002.
[3] Web resources of the Florida Institute for Human and Machine Cognition (IHMC).
[4] Goutam Kumar Saha, "Software Fault Avoidance Issues," ACM Ubiquity, Vol. 7, Issue 46, 2006.
[5] Goutam Kumar Saha, "Software Based Fault Tolerance - a Survey," ACM Ubiquity, Vol. 7, Issue 25, 2006.
[6] Goutam Kumar Saha, "Software Based Fault Detection in Microprocessors," in press, IEEE Potentials, IEEE, USA, 2007.
[8] Goutam Kumar Saha, "Web Ontology Language (OWL) and Semantic Web," ACM Ubiquity, Vol. 8, Issue 35, 2007.
[9] D. K. Pradhan, "Fault-Tolerant Computer System Design," Prentice Hall, 1996.
[10] R.R. Brooks, S.S. Iyengar, "Robust Distributed Computing and Sensing Algorithm," Computer, Volume 29, Issue 6, June 1996, Page(s):53 - 60.
[11] Ross A. Gagliano, "Towards Consciousness: Ontology, Language, and Intelligence," In: Advances in Research of Human Consciousness. Windsor, Canada: International Institute for Advanced Studies in Systems Research and Cybernetics, 39-43, 1994.
[12] Lawrence Bernstein, "Software Fault Tolerance Forestalls Crashes: To Err is Human; to Forgive is Fault Tolerant," chapter, Book- Advances in Computers Volume 58, Highly Dependable Software, Marvin Zelkowitz (ed), Academic Press. pp 240 - 285.
[13] J. A. Clark, D. K. Pradhan, "REACT: An Integrated Tool for the Design of Dependable Computer Systems", in "Foundations of Dependable Computing, Models and Frame-works for Dpendable Systems", G. M. Koob, C. G. Lau (ed.), Kluwer, pp. 169-192, 1994.

About the Author
In his last nearly twenty years' R&D and teaching experience, Goutam Kumar Saha has worked as a scientist in LRDE, Defence Research & Development Organisation, Bangalore and at the Electronics Research & Development Centre of India, Calcutta. At present, he is with the Centre for Development of Advanced Computing, Kolkata, India, as a Scientist-F. He is a fellow in IETE and senior member in IEEE, Computer Society of India, and ACM Fellow nominee etc. He has received various awards, scholarships and grants from national and international organizations. He is a referee of CSI Journal, AMSE Journal (France), IJCPOL (USA), IJCIS (Canada) and of an IEEE Journal/Magazine (USA). He is an associate editor of the ACM Ubiquity (USA), International Journal of the Latin American Center for Informatics Studies (CLEIJ) and of the International Journal of Computing and Information Sciences (Canada). He is a Chair and Member of the Program Committee of the WSNEXT / UBICOMM 2007 (French Polynesia), UBICOMM 2008 (France), IEEE Computer Society Press, CONFENIS2007 (Beijing) etc. His fields of interest include software based fault tolerance, web technology, EIS, Ontology Engineering and Natural Language Processing. He can be reached via,,


Fundamental Concepts of Dependability

— SteveAllie, Fri, 13 Apr 2012 18:13:27 UTC

[1] A. Avizienis, J.C. Laprie, B. Randell, "Fundamental Concepts of Dependability," Research Report No. 1145, LAAS-CNRS, 2001

— maryam_ansari, Mon, 10 Oct 2011 11:41:44 UTC

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