Streams, structures, spaces, scenarios, societies (5s): A formal model for digital libraries

ABSTRACT

Digital libraries (DLs) are complex information systems and therefore demand formal foundations lest development efforts diverge and interoperability suffers. In this article, we propose the fundamental abstractions of Streams, Structures, Spaces, Scenarios, and Societies (5S), which allow us to define digital libraries rigorously and usefully. Streams are sequences of arbitrary items used to describe both static and dynamic (e.g., video) content. Structures can be viewed as labeled directed graphs, which impose organization. Spaces are sets with operations on those sets that obey certain constraints. Scenarios consist of sequences of events or actions that modify states of a computation in order to accomplish a functional requirement. Societies are sets of entities and activities and the relationships among them. Together these abstractions provide a formal foundation to define, relate, and unify concepts---among others, of digital objects, metadata, collections, and services---required to formalize and elucidate "digital libraries". The applicability, versatility, and unifying power of the 5S model are demonstrated through its use in three distinct applications: building and interpretation of a DL taxonomy, informal and formal analysis of case studies of digital libraries (NDLTD and OAI), and utilization as a formal basis for a DL description language.

REFERENCES

• 1: Serge Abiteboul , Peter Buneman , Dan Suciu, Data on the Web: from relations to semistructured data and XML, Morgan Kaufmann Publishers Inc., San Francisco, CA, 1999
• 2: Abiteboul, S., Quass, D., McHugh, J., Widom, J., and Wiener, J. L. 1997. The Lorel query language for semistructured data. Int. J. Digit. Lib. 1, 1 (Apr.) 5--19.
• 3: Marc Abrams , Constantinos Phanouriou , Alan L. Batongbacal , Stephen M. Williams , Jonathan E. Shuster, UTML: an appliance-independent XML user interface language, Computer Networks: The International Journal of Computer and Telecommunications Networking, v.31 n.11-16, p.1695-1708, May 17, 1999
• 4: Kenneth M. Anderson , Aaron Andersen , Neet Wadhwani , Laura M. Bartolo, Metis: lightweight, flexible, and Web-based workflow services for digital libraries, Proceedings of the 3rd ACM/IEEE-CS joint conference on Digital libraries, May 27-31, 2003, Houston, Texas
• 5: Atkins, A., Fox, E., France, R., and Suleman, H. 2001. Interoperability metadata standard for electronic theses and dissertations. http://www.ndltd.org/standards/metadata/current.html.
• 6: David L. Atkins , Thomas Ball , Glenn Bruns , Kenneth Cox, Mawl: A Domain-Specific Language for Form-Based Services, IEEE Transactions on Software Engineering, v.25 n.3, p.334-346, May 1999 [doi>10.1109/32.798323]
• 7: Baeza-Yates, R. and Navarro, G. 2000. XQL and Proximal Nodes. In Proceedings of the ACM SIGIR 2000---Workshop on XML and Information Retrieval (Athens, Greece, July). ACM, New York, Reading, Mass.
• 8: Ricardo A. Baeza-Yates , Berthier Ribeiro-Neto, Modern Information Retrieval, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1999
• 9: Bayley, K. D. 1994. Typologies and Taxonomies---An Introduction to Classification Techniques. SAGE Publications, Thousand Oaks, Calif.
• 10: Murat Bayraktar , Change Zhang , Bharadwaj Vadapalli , Neill A. Kipp , Edward A. Fox, A Web art gallery, Proceedings of the third ACM conference on Digital libraries, p.277-278, June 23-26, 1998, Pittsburgh, Pennsylvania, United States [doi>10.1145/276675.276727]
• 11: C. Beeri, A formal approach to object-oriented databases, Data & Knowledge Engineering, v.5 n.4, p.353-382, Oct. 1990 [doi>10.1016/0169-023X(90)90020-E]
• 12: Belkin, N. J., Oddy, R. N., and Brooks, H. M. 1982. ASK for information retrieval. J. Document. 33, 2 (June), 61--71.
• 13: Berners-Lee, T., Hendler, J., and Lassila, O. 2001. The semantic web. Sci. Amer. 284, 5 (May).
• 14: Grady Booch, UML in action, Communications of the ACM, v.42 n.10, p.26-28, Oct. 1999 [doi>10.1145/317665.317672]
• 15: Christine L. Borgman, What are digital libraries? Competing visions, Information Processing and Management: an International Journal, v.35 n.3, p.227-243, May 1999 [doi>10.1016/S0306-4573(98)00059-4]
• 16: Borlund, P. and Ingwersen, P. 1997. The development of a method for the evaluation of interactive information retrieval systems. J. Document. 53, 3 (June), 225--250.
• 17: Donatella Castelli , Carlo Meghini , Pasquale Pagano, Foundations of a Multidimensional Query Language for Digital Libraries, Proceedings of the 6th European Conference on Research and Advanced Technology for Digital Libraries, p.251-265, September 16-18, 2002
• 18: R. G. G. Cattell , Douglas K. Barry , Dirk Bartels , Mark Berler , Jeff Eastman , Sophie Gamerman , David Jordan , Adam Springer , Henry Strickland , Drew Wade, The object database standard: ODMG 2.0, Morgan Kaufmann Publishers Inc., San Francisco, CA, 1997
• 19: Clarke, C. L., Cormack, G. V., and Burkowski, F. J. 1995. An algebra for structured text search and a framework for its implementation. Comput. J. 38, 43--56.
• 20: E. F. Codd, A relational model of data for large shared data banks, Communications of the ACM, v.13 n.6, p.377-387, June 1970 [doi>10.1145/362384.362685]
• 21: James H. Coombs , Allen H. Renear , Steven J. DeRose, Markup systems and the future of scholarly text processing, Communications of the ACM, v.30 n.11, p.933-947, Nov. 1987 [doi>10.1145/32206.32209]
• 22: Thomas T. Cormen , Charles E. Leiserson , Ronald L. Rivest, Introduction to algorithms, MIT Press, Cambridge, MA, 1990
• 23: Andy Crabtree , Michael B. Twidale , Jon O'Brien , David M. Nichols, Talking in the library: implications for the design of digital libraries, Proceedings of the second ACM international conference on Digital libraries, p.221-228, July 23-26, 1997, Philadelphia, Pennsylvania, United States [doi>10.1145/263690.263824]
• 24: Fabio Crestani , Mounia Lalmas , Cornelis J. Van Rijsbergen , Iain Campbell, “Is this document relevant?…probably”: a survey of probabilistic models in information retrieval, ACM Computing Surveys (CSUR), v.30 n.4, p.528-552, Dec. 1998 [doi>10.1145/299917.299920]
• 25: Lynne Davis , Melissa Dawe, Collaborative design with use case scenarios, Proceedings of the 1st ACM/IEEE-CS joint conference on Digital libraries, p.146-147, January 2001, Roanoke, Virginia, United States [doi>10.1145/379437.379472]
• 26: Martin D. Davis , Ron Sigal , Elaine J. Weyuker, Computability, complexity, and languages (2nd ed.): fundamentals of theoretical computer science, Academic Press Professional, Inc., San Diego, CA, 1994
• 27: Maria Cristina Ferreira de Oliveira , Marcelo Augusto Santos Turine , Paulo Cesar Masiero, A statechart-based model for hypermedia applications, ACM Transactions on Information Systems (TOIS), v.19 n.1, p.28-52, Jan. 2001 [doi>10.1145/366836.366869]
• 28: DOMTeam. 2003. Document object model (DOM) homepage. http://www.w3.org/DOM/.
• 29: Andy Dong , Alice M. Agogino, Design principles for the information architecture of a SMET education digital library, Proceedings of the 1st ACM/IEEE-CS joint conference on Digital libraries, p.314-321, January 2001, Roanoke, Virginia, United States [doi>10.1145/379437.379699]
• 30: Dushay, N. 2001. Using structural metadata to localize experience of digital content. Tech. Rep. cs.DL/0112017, The Computing Research Repository (CoRR).
• 31: David Ellis, The physical and cognitive paradigms in information retrieval research, Journal of Documentation, v.48 n.1, p.45-64, March 1992 [doi>10.1108/eb026889]
• 32: Flanagan, J. W., Fox, E. A., and Fan, W. 2003. Managing complex information applications: An archaeology digital library. http://feathers.dlib.vt.edu/.
• 33: Foskett, D. J. 1980. Thesaurus. In Encyclopedia of Library and Information Science---Volume 30. Marcel Dekker, New York, 416--462.
• 34: Edward A. Fox , Robert M. Akscyn , Richard K. Furuta , John J. Leggett, Digital libraries, Communications of the ACM, v.38 n.4, p.22-28, April 1995 [doi>10.1145/205323.205325]
• 35: Fox, E. A., Eaton, J. L., McMillan, G., Kipp, N. A., Mather, P., McGonigle, T., Schweiker, W., and DeVane, B. 1997. Networked Digital Library of Theses and Dissertations: An international effort unlocking university resources. D-Lib Mag. 3, 9 (Sept).
• 36: Edward A. Fox , Gary Marchionini, Toward a worldwide digital library, Communications of the ACM, v.41 n.4, p.29-32, April 1998 [doi>10.1145/273035.273043]
• 37: France, R. K., Gonçalves, M. A., and Fox, E. A. 2002. MARIAN digital library system. http://www.dlib.vt.edu/products/marian.html.
• 38: Norbert Fuhr , Kai Groβjohann, XIRQL: An XML query language based on information retrieval concepts, ACM Transactions on Information Systems (TOIS), v.22 n.2, p.313-356, April 2004 [doi>10.1145/984321.984326]
• 39: Fuhr, N. 2000. XIRQL---An extension of XQL for information retrieval. In Proceedings of the ACM SIGIR 2000---Workshop on XML and Information Retrieval (Athens, Greece, July). ACM, New York.
• 40: Furuta, R. 1994. Defining and using structure in digital documents. In Proceedings of the 1st Annual Conference on the Theory and Practice of Digital Libraries (College Station, Tex.).
• 41: R. Furuta , V. Quint , J. Andre, Interactively editing structured documents, Electronic Publishing—Origination, Dissemination, and Design, v.1 n.1, p.19-44, April 1989
• 42: Garza-Salazar, D. A. 2001. Phronesis. http://copernico.mty.itesm.mx/ tempo/Proyectos/.
• 43: Gladney, H., Fox, E. A., Ahmed, Z., Ashany, R., Belkin, N. J., and Zemankova, M. 1994. Digital library: Gross Structure and Requirements: Report from a March 1994 Workshop. In Proceedings of the 1st Annual Conference on the Theory and Practice of Digital Libraries (Texas), 101--107.
• 44: H. M. Gladney , Arthur Cantu, Authorization management for digital libraries, Communications of the ACM, v.44 n.5, p.63-65, May 2001 [doi>10.1145/374308.374343]
• 45: Godement, R. 1969. Algebra. Kershaw Publ. Co. Ltd, London, England.
• 46: Dion Goh , John Leggett, Patron-augmented digital libraries, Proceedings of the fifth ACM conference on Digital libraries, p.153-163, June 02-07, 2000, San Antonio, Texas, United States [doi>10.1145/336597.336656]
• 47: Charles F. Goldfarb , Paul Prescod, The XML handbook, Prentice Hall PTR, Upper Saddle River, NJ, 1999
• 48: Gonçalves, M. A. 2003. Digital libraries: Formal theory, language, design, generation, quality and evaluation. Ph.D. preliminary exam, Virginia Tech, Blacksburg, VA.
• 49: Marcos André , Gonçalves , Edward A. Fox, 5SL: a language for declarative specification and generation of digital libraries, Proceedings of the 2nd ACM/IEEE-CS joint conference on Digital libraries, July 14-18, 2002, Portland, Oregon, USA [doi>10.1145/544220.544276]
• 50: Gonçalves, M. A., Fox, E. A., Watson, L. T., and Kipp, N. 2003. Streams, structures, spaces, scenarios, societies (5S): A formal model for digital libraries. Tech. Rep. 03-04, Virginia Tech.
• 51: Marcos André Gonçalves , Robert K. France , Edward A. Fox, MARIAN: Flexible Interoperability for Federated Digital Libraries, Proceedings of the 5th European Conference on Research and Advanced Technology for Digital Libraries, p.173-186, September 04-09, 2001
• 52: Marcos André Gonçalves , Paul Mather , Jun Wang , Ye Zhou , Ming Luo , Ryan Richardson , Rao Shen , Liang Xu , Edward A. Fox, Java MARIAN: From an OPAC to a Modern Digital Library System, Proceedings of the 9th International Symposium on String Processing and Information Retrieval, p.194-209, September 11-13, 2002
• 53: Gonçalves, M. A., Zafer, A. A., Ramakrishnan, N., and Fox, E. A. 2001. Modeling and building personalized digital libraries with PIPE and 5SL. In Proceedings of the Joint DELOS-NSF Workshop on Personalization and Recommender Systems in Digital Libraries (Dublin, Ireland).
• 54: Lenwood S. Heath , Deborah Hix , Lucy T. Nowell , William C. Wake , Guillermo A. Averboch , Eric Labow , Scott A. Guyer , Dennis J. Brueni , Robert K. France , Kaushai Dalal , Edward A. Fox, Envision: a user-centered database of computer science literature, Communications of the ACM, v.38 n.4, p.52-53, April 1995 [doi>10.1145/205323.376383]
• 55: Pei Hsia , Jayarajan Samuel , Jerry Gao , David Kung , Yasufumi Toyoshima , Cris Chen, Formal Approach to Scenario Analysis, IEEE Software, v.11 n.2, p.33-41, March 1994 [doi>10.1109/52.268953]
• 56: Karen Sparck Jones , Peter Willett, Readings in information retrieval, Morgan Kaufmann Publishers Inc., San Francisco, CA, 1997
• 57: Hal R. Varian , Brian Kahin, Internet Publishing and beyond: The Economics of Digital Information and Intellectual Property, MIT Press, Cambridge, MA, 2000
• 59: Kalinichenko, L. A., Briukhov, D. O., Skvortsov, N. A., and Zakharov, V. N. 2000. Infrastructure of the subject mediating environment aiming at semantic interoperability of heterogeneous digital library collections. In Proceedings of the 2nd Russian Scientific Conference on Digital Libraries: Advanced Methods and Technologies.
• 60: Henry Kautz , Bart Selman , Mehul Shah, Referral Web: combining social networks and collaborative filtering, Communications of the ACM, v.40 n.3, p.63-65, March 1997 [doi>10.1145/245108.245123]
• 61: Kelapure, R., Gonçalves, M. A., and Fox, E. A. 2003. Scenario-based generation of digital library services. In Proceedings 7th European Conference Research and Advanced Technology for Digital Libraries (ECDL). Lecture Notes in Computer Science, vol. 2760, Springer-Verlag, New York. (Trondheim, Norway).
• 62: Thomas R. Kochtanek , Karen K. Hein, Delphi study of digital libraries, Information Processing and Management: an International Journal, v.35 n.3, p.245-254, May 1999 [doi>10.1016/S0306-4573(98)00060-0]
• 63: Morten Kyng, Creating contexts for design, Scenario-based design: envisioning work and technology in system development, John Wiley & Sons, Inc., New York, NY, 1995
• 64: Alberto H. F. Laender , Berthier Ribeiro-Neto , Altigran S. da Silva, DEByE - Date extraction by example, Data & Knowledge Engineering, v.40 n.2, p.121-154, February 2002 [doi>10.1016/S0169-023X(01)00047-7]
• 65: Lagoze, C. 1996. The Warwick framework: A container architecture for diverse sets of metadata. D-Lib Mag. 2, 7 (July 15).
• 66: Carl Lagoze , Herbert Van de Sompel, The open archives initiative: building a low-barrier interoperability framework, Proceedings of the 1st ACM/IEEE-CS joint conference on Digital libraries, p.54-62, January 2001, Roanoke, Virginia, United States [doi>10.1145/379437.379449]
• 67: Axel van Lamsweerde , Laurent Willemet, Inferring Declarative Requirements Specifications from Operational Scenarios, IEEE Transactions on Software Engineering, v.24 n.12, p.1089-1114, December 1998 [doi>10.1109/32.738341]
• 68: Lesk, M. 1999. Expanding digital library research: Media, genre, place and subjects. In Proceedings of the International Symposium on Digital Libraries 1999: ISDL'99 (Tsukuba, Ibaraki, Japan).
• 69: David M. Levy , Catherine C. Marshall, Going digital: a look at assumptions underlying digital libraries, Communications of the ACM, v.38 n.4, p.77-84, April 1995 [doi>10.1145/205323.205346]
• 70: Library Of Congress. 2003. METS---Metadata Encoding and Transmission Standard. http:// www.loc.gov/standards/mets/.
• 71: J. C. R. Licklider, Libraries of the Future, The MIT Press, 1965
• 72: Raymond A. Lorie, Long term preservation of digital information, Proceedings of the 1st ACM/IEEE-CS joint conference on Digital libraries, p.346-352, January 2001, Roanoke, Virginia, United States [doi>10.1145/379437.379726]
• 73: Dario Lucarella , Antonella Zanzi, A visual retrieval environment for hypermedia information systems, ACM Transactions on Information Systems (TOIS), v.14 n.1, p.3-29, Jan. 1996 [doi>10.1145/214174.214175]
• 74: Wendy E. Mackay , Michel Beaudouin-Lafon, DIVA: exploratory data analysis with multimedia streams, Proceedings of the SIGCHI conference on Human factors in computing systems, p.416-423, April 18-23, 1998, Los Angeles, California, United States [doi>10.1145/274644.274701]
• 75: Miller, T. 1999. Annotation system for a collection of ETDs. http://www.ndltd.org/ndltd-sc/990416/annsystem.pdf.
• 76: Gonzalo Navarro , Ricardo Baeza-Yates, Proximal nodes: a model to query document databases by content and structure, ACM Transactions on Information Systems (TOIS), v.15 n.4, p.400-435, Oct. 1997 [doi>10.1145/263479.263482]
• 77: NDLTD. 2003. Networked Digital Library of Theses and Dissertations. http://www.ndltd.org.
• 78: Michael L. Nelson , Kurt Maly, Buckets: smart objects for digital libraries, Communications of the ACM, v.44 n.5, p.60-62, May 2001 [doi>10.1145/374308.374342]
• 79: Svetlozer Nestorov , Serge Abiteboul , Rajeev Motwani, Inferring structure in semistructured data, ACM SIGMOD Record, v.26 n.4, p.39-43, Dec. 1997 [doi>10.1145/271074.271084]
• 80: Fernando A. Das Neves , Edward A. Fox, A study of user behavior in an immersive virtual environment for digital libraries, Proceedings of the fifth ACM conference on Digital libraries, p.103-111, June 02-07, 2000, San Antonio, Texas, United States [doi>10.1145/336597.336648]
• 81: OAI. 2001. Open Archives Initiative Protocol for Metadata Harvesting---v.2.0. http://www.openarchives.org/OAI/openarchivesprotocol.html.
• 82: Douglas W. Oard , Carol Peters, Multilingual information discovery and access (MIDAS), Proceedings of the fourth ACM conference on Digital libraries, p.265, August 11-14, 1999, Berkeley, California, United States [doi>10.1145/313238.313449]
• 83: Andreas Oberweis , Peter Sander, Information system behavior specification by high level Petri nets, ACM Transactions on Information Systems (TOIS), v.14 n.4, p.380-420, Oct. 1996 [doi>10.1145/237496.237498]
• 84: Ryuichi Ogawa , Hiroaki Harada , Asao Kaneko, Scenario-based hypermedia: a model and a system, Hypertext: concepts, systems and applications, Cambridge University Press, New York, NY, 1992
• 85: Robert Prince , Jianwen Su , Hong Tang , Yonggang Zhao, The design of an interactive online help desk in the Alexandria Digital Library, Proceedings of the international joint conference on Work activities coordination and collaboration, p.217-226, February 22-25, 1999, San Francisco, California, United States
• 86: Naren Ramakrishnan, PIPE: Web Personalization by Partial Evaluation, IEEE Internet Computing, v.4 n.6, p.21-31, November 2000 [doi>10.1109/4236.895012]
• 87: Ranganathan, S. R. 1965. A Descriptive Account of Colon Classification. Sarada Ranganathan Endowment for Library Science, Bangalore, India.
• 88: Reddy, R. and Wladawsky-Berger, I. 2001. Digital libraries: Universal access to human knowledge---A report to the president. President's Information Technology Advisory Committee (PITAC), Panel on Digital Libraries. http://www.itrd.gov/pubs/pitac/pitac-dl-9feb01.pdf.
• 89: Robertson, S. E. 1977. The probability ranking principle in IR. Doc. J. 33, 294--304.
• 90: Robertson, S. E. and Jones, K. S. 1976. Relevance weighting of search terms. J. ASIS 27, 3 (May--June), 129--146.
• 91: Mary Beth Rosson, Integrating development of task and object models, Communications of the ACM, v.42 n.1, p.49-56, Jan. 1999 [doi>10.1145/291469.293168]
• 92: Mary Beth Rosson , John M. Carroll, Object-oriented design from user scenarios, Conference companion on Human factors in computing systems: common ground, p.342-343, April 13-18, 1996, Vancouver, British Columbia, Canada [doi>10.1145/257089.257359]
• 93: G. Salton , M. E. Lesk, The SMART automatic document retrieval systems—an illustration, Communications of the ACM, v.8 n.6, p.391-398, June 1965 [doi>10.1145/364955.364990]
• 94: G. Salton , A. Wong , C. S. Yang, A vector space model for automatic indexing, Communications of the ACM, v.18 n.11, p.613-620, Nov. 1975 [doi>10.1145/361219.361220]
• 95: Saracevic, T. 1975. Relevance: a review and a framework for thinking on the notion in information science. J. ASIS 26, 321--343.
• 96: Schauble, P. and Smeaton, A. F. 1998. Summary report of the series of joint NSF-EU working groups on future directions for digital library research: An international research agenda for digital libraries. http://www.ercim.org/publication/ws-proceedings.
• 97: Michael F. Schwartz , David C. M. Wood, Discovering shared interests using graph analysis, Communications of the ACM, v.36 n.8, p.78-89, Aug. 1993 [doi>10.1145/163381.163402]
• 98: Douglas E. Shackelford , John B. Smith , F. Donelson Smith, The architecture and implementation of a distributed hypermedia storage system, Proceedings of the fifth ACM conference on Hypertext, p.1-13, November 14-18, 1993, Seattle, Washington, United States [doi>10.1145/168750.168753]
• 99: Shannon, C. E. 1948. A mathematical theory of communication. Bell Syst. Tech. J. 27, 379--423, 623--656.
• 100: Edleno Silva de Moura , Gonzalo Navarro , Nivio Ziviani , Ricardo Baeza-Yates, Fast and flexible word searching on compressed text, ACM Transactions on Information Systems (TOIS), v.18 n.2, p.113-139, April 2000 [doi>10.1145/348751.348754]
• 101: Mukesh Singhal , Niranjan G. Shivaratri , Niranjan Shivaratro, Advanced Concepts in Operating Systems, McGraw-Hill, Inc., New York, NY, 1994
• 102: J. M. Spivey, Understanding Z: a specification language and its formal semantics, Cambridge University Press, New York, NY, 1988
• 103: Staples, T., Wayland, R., and Payette, S. 2003. The FEDORA project---An open-source digital object repository management system. D-Lib Maga. 9, 4 (Apr.).
• 104: Alistair Sutcliffe, A Technique Combination Approach to Requirements Engineering, Proceedings of the 3rd IEEE International Symposium on Requirements Engineering (RE'97), p.65, January 05-08, 1997
• 105: Alistair G. Sutcliffe , Neil A. M. Maiden , Shailey Minocha , Darrel Manuel, Supporting Scenario-Based Requirements Engineering, IEEE Transactions on Software Engineering, v.24 n.12, p.1072-1088, December 1998 [doi>10.1109/32.738340]
• 106: Jean Tague , Airi Salminen , Charles McClellan, Complete formal model for information retrieval systems, Proceedings of the 14th annual international ACM SIGIR conference on Research and development in information retrieval, p.14-20, October 13-16, 1991, Chicago, Illinois, United States [doi>10.1145/122860.122862]
• 107: Robert Tansley , Mick Bass , David Stuve , Margret Branschofsky , Daniel Chudnov , Greg McClellan , MacKenzie Smith, The DSpace institutional digital repository system: current functionality, Proceedings of the 3rd ACM/IEEE-CS joint conference on Digital libraries, May 27-31, 2003, Houston, Texas
• 108: Howard Turtle , W. Bruce Croft, Evaluation of an inference network-based retrieval model, ACM Transactions on Information Systems (TOIS), v.9 n.3, p.187-222, July 1991 [doi>10.1145/125187.125188]
• 109: Jeffrey D. Ullman, Principles of database and knowledge-base systems, Vol. I, Computer Science Press, Inc., New York, NY, 1988
• 110: Vickery, B. C. 1965. Faceted classification schemes. In Rutgers Series for the Intellectual Organization of Information---Volume 5. Rutgers University Press, New Brunswick, N.J.
• 111: VTLS. 2001. VTLS. http://www.vtls.com.
• 112: W3C. 1998. Resource Description Framework (RDF) Model and Syntax Specification. http:// www.w3.org/TR/WD-rdf-syntax/.
• 113: W3C. 2000a. Resource Description Framework (RDF) Schema Specification 1.0. http://www.w3. org/TR/2000/CR-rdf-schema-20000327/.
• 114: W3C. 2000b. XML Schema Part 0: Primer, W3C Working Draft. http://www.w3.org/TR/ xmlschema-0.
• 115: W3C. 2001. Mathematical Markup Language (MathML). http://www.w3.org/Math/.
• 116: Wang, B. 1999. A hybrid system approach for supporting digital libraries. Int. J. Dig. Lib. 2, 2-3, 91--110.
• 117: Weigang Wang , Roy Rada, Structured hypertext with domain semantics, ACM Transactions on Information Systems (TOIS), v.16 n.4, p.372-412, Oct. 1998 [doi>10.1145/291128.291132]
• 118: Gio Wiederhold, Digital libraries, value, and productivity, Communications of the ACM, v.38 n.4, p.85-96, April 1995 [doi>10.1145/205323.205347]
• 119: Wilkison, R. and Fuller, M. 1996. Integration of information retrieval and hypertext via structure. In Inf. Ret. Hyper. Kluwer Academic Publishers, 257--271.
• 120: Glynn Winskel, The formal semantics of programming languages: an introduction, MIT Press, Cambridge, MA, 1993
• 121: Ian H. Witten , Stefan J. Boddie , David Bainbridge , Rodger J. McNab, Greenstone: a comprehensive open-source digital library software system, Proceedings of the fifth ACM conference on Digital libraries, p.113-121, June 02-07, 2000, San Antonio, Texas, United States [doi>10.1145/336597.336650]
• 122: Tak W. Yan , Hector Garcia-Molina, The SIFT information dissemination system, ACM Transactions on Database Systems (TODS), v.24 n.4, p.529-565, Dec. 1999 [doi>10.1145/331983.331992]
• 123: Zhu, Q., Gonçalves, M. A., Shen, R., Cassell, L., and Fox, E. A. 2003. Visual semantic modeling of digital libraries. In Proceedings 7th European Conference Research and Advanced Technology for Digital Libraries (ECDL). (Trondheim, Norway). Lecture Notes on Computer Science, vol. 2769. Springer-Verlag, New York.
• 124: Lee L. Zia, The NSF national science, mathematics, engineering, and technology education digital library program, Communications of the ACM, v.44 n.5, p.83, May 2001 [doi>10.1145/374308.375359]
• 125: Nivio Ziviani , Edleno Silva de Moura , Gonzalo Navarro , Ricardo Baeza-Yates, Compression: A Key for Next-Generation Text Retrieval Systems, Computer, v.33 n.11, p.37-44, November 2000 [doi>10.1109/2.881693]
• 126: Zubair, M., Maly, K., Ameerally, I., and Nelson, M. 2000. Dynamic construction of federated digital libraries. In Proceedings of the 9th International World Wide Web Conference Amsterdam, The Netherlands.

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.3 INFORMATION STORAGE AND RETRIEVAL
      H.3.7 Digital Libraries

General Terms:
Theory

Keywords:
applications., definitions, foundations, taxonomy