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Formal specification languages in knowledge and software engineering

Published online by Cambridge University Press:  07 July 2009

Dieter Fensel
Affiliation:
Department SWI, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands (email: [email protected])

Abstract

During the last few years, a number of formal specification languages for knowledge-based systems (KBS) have been developed. Characteristics of such systems are a complex knowledge base and an inference engine which uses this knowledge to solve a given problem. Languages for KBS have to cover both these aspects. They have to provide a means to specify a complex and large amount of knowledge and they have to provide a means to specify the dynamic reasoning behaviour of a KBS. Nevertheless, KBS are just a specific type of software system. Therefore, it seems quite natural to compare formal languages for specifying KBS with formal languages which were developed by the software community for specifying software systems. That is the subject of this paper.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1995

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References

Aben, M, 1995. Formal methods in knowledge engineering, PhD dissertation, University of Amsterdam.Google Scholar
Alford, M, 1990. “SREM at the age of eight: the distributed computing design system” In: Thayer, RH et al. , eds., System and Software Requirements Engineering, IEEE PressGoogle Scholar
Andrews, D and Ince, D, 1991. Practical Formal Methods with VDM, McGraw-Hill.Google Scholar
Andersen, M, Elmstrøm, R, Lassen, PB and Larsen, PG, 1992. “Making specifications executable—using IPTES Meta-IVMicroprocessing and Microprogramming 35.Google Scholar
Angele, J., 1993. Operationalisierung des Modells der Expertise mit KARL, Infix, St. Augustin.Google Scholar
Angele, J, Fensel, D, Landes, D, Neubert, S and Studer, R, 1993. “Model-based and incremental knowledge engineering: The MIKE approach” In: Cuena, J, ed., Knowledge Oriented Software Design, IFIP Transactions A-27, Elsevier.Google Scholar
Angele, J, Fensel, D and Studer, R, 1994. “The model of expertise in KARL.” In: Proceedings of the 2nd World Congress on Expert Systems Lisbon/Estoril, Portugal, 01 10–14.Google Scholar
Baeten, JCM, 1990. Applications of Process Algebra, Cambridge Tracts in Theoretical Computer Science, no 17, Cambridge University Press.Google Scholar
Baeten, JCM and Weijland, WP, 1990. Process Algebra, Cambridge Tracts in Theoritical Computer Science, no 18, Cambridge University Press.CrossRefGoogle Scholar
Balzer, R and Goldman, N, 1979. “Principles of good software specification and their implications for specification language” In: Proceedings of Reliable Software (SRS), Boston, MA.Google Scholar
Balzer, RM, Goldman, NM and Wile, DS, 1982. “Operational specifications as the basis for rapid prototypingACM SIGSOFT Software Engineering Notes 7(5).CrossRefGoogle Scholar
Bauer, FL, Ehler, H, Horsch, A, Möller, B, Partsch, H, Paukner, O and Pepper, P, 1987. The Munich Project CIP, vol II: The Program Transformation System CIP-S, Lecture Notes on Computer Science, no 292, Springer-Verlag.Google Scholar
Beckert, B and Posegga, J, 1995. “leanEA: A Poor Man's Evolving Algebra Compiler” Research report, University of Karlsruhe.CrossRefGoogle Scholar
Bell, TE, Bixler, CD and Dyer, ME, 1977. “An extendable approach to computer-aided software requirements engineeringIEEE Transactions on Software Engineering 3(1).Google Scholar
Berry, DC, 1987. “The problem of implicit knowledgeExpert systems 4(3).Google Scholar
Bicarregui, JC, Fitzgerald, JS, Lindsay, PA, Moore, R and Ritchie, B, 1994. Proof in VDM: A Practitioner's Guide, Springer-Verlag.Google Scholar
Bidoit, M, 1989. PLUSS, un language pour le developpement de specifications algebriques modulaires, These d'Etat, University Paris Dus, Orsay.Google Scholar
Bidoit, M, Kreowski, HJ, Lescane, P, Orejas, F and Sannella, D, eds., 1991. Algebraic System Specification and Development, Lecture Notes in Computer Science, no 501, Springer-Verlag.CrossRefGoogle Scholar
Bjorner, D, Hoare, CAR and Langmaack, H, eds., 1990. VDM'90. VDM and β—Formal Methods in Software Development, Lecture Notes in Computer Science, no 428, Springer-Verlag.CrossRefGoogle Scholar
Börger, E, Gurevich, Y and Rosenzweig, D, 1994. “The Bakery algorithm: yet another specification and verification” In: Börger, EB, ed., Specification and Validation Methods, Oxford University Press.Google Scholar
Brazier, FMT, Keplicz, BD, Jennings, NR and Treur, J, 1995a. “Formal specifications of multi-agent systems: a real-world case” In: Proceedings of the 1st International Conference on Multi-Agent Systems (ICMAS-95), San Francisco, CA, 06 1214.Google Scholar
Brazier, FMT and Treur, J, 1994. “User centered knowledge-based system design: a formal modelling approach” In: Steels, L et al. , eds., A Future for Knowledge Acquisition, 8th European Knowledge Acquisition Workshop, EKAW-94 Lecture Notes in Artificial Intelligence, no 867, Springer-Verlag.Google Scholar
Brazier, FMT, Treur, J, Wijngaards, NJE and Willems, M, 1995b. “Formal specification of hierarchically (de)composed tasks” In: Proceedings of the 9th Banff Knowledge Acquisition For Knowledge-Based Systems Workshops (KAW-95), Banff, Alberta, Canada, 02 26 03 3.Google Scholar
Breuker, JA and van de Velde, W, eds., 1994. The CommonKADS Library for Expertise Modelling, lOS Press.Google Scholar
Bonner, AJ and Kifer, M, 1993. “Transaction logic programming” In: Proceedings of the 10th International Conference on Logic Programming (ICLP) Budapest, Hungary, 06 21–24.Google Scholar
Bourdeau, RH and Cheng, BHC, 1995. “A formal semantics for object model diagramsIEEE Transaction on Software Engineering 21(10).Google Scholar
Brodie, ML, 1984. “On the development of data models” In: Brodie, et al. , eds., On Conceptual Modeling, Springer-Verlag.Google Scholar
Brodie, ML and Ridjanovic, D, 1984. “On the design and specification of database transactions” In: Brodie, et al. , eds., On Conceptual Modeling, Springer-Verlag.Google Scholar
Brooking, AG, 1986. “The analysis phase in development of knowledge-based systems” In: Gale, WA, ed., Al and Statistic, Addison-Wesley.Google Scholar
Chandrasekaran, B, 1986. “Generic tasks in knowledge-based reasoning: high-level building blocks for expert system designIEEE Expert 1(3).Google Scholar
Clancey, WJ, 1987. “From Guidon to Neomycin and Heracles in twenty short lessons” In: van Lamsweerde, A, ed., Current Issues in Expert Systems, Academic Press.Google Scholar
Coad, P and Yourdon, E, 1991. Object-Oriented Analysis, 2nd ed., Yourdon Press.Google Scholar
Craigen, D, Gerhart, S and Ralston, T, 1993. An International Survey of Industrial Applications of Formal Methods, vol. 1 and 2, U.S. Department of Commerce, National Institute of Standards and Technology, Gaithersburg, report NISTGCR 93/626. ftp nemo.ncsl.nist.gov, pub/ahis/formal–methods.CrossRefGoogle Scholar
(A short version appeared as Gerhart, S, Craigen, D and Ralston, T, 1993, “Observations on industrial practice using formal methods” In: Proceedings of the 15th International Conference on Software Engineering (ICSE-93) 05 17–21, Baltimore, Maryland.)Google Scholar
Doberkat, E-E, 1994. Generating an Algebraic Specification from an ER-Model STW Memo, no ISSN 0933- 7725, University of Dortmund, Germany.Google Scholar
Doberkat, E-E and Fox, D, 1989. Software Prototyping mit SETL, Leitfäden und Monographien der Informatik, Teubner-Verlag, Stuttgart.Google Scholar
Dorfman, M, 1990. “System and software requirements engineering” In: Thayer, RH and Dorfman, M, eds., System and Software Requirements Engineering, IEEE Press.Google Scholar
Ehrig, H and Mahr, B, eds., 1985. Fundamentals of Algebraic Specifications 1, Springer-Verlag.CrossRefGoogle Scholar
Ehrig, H and Mahr, B, eds., 1990. Fundamentals of Algebraic Specifications 2, Springer-Verlag.CrossRefGoogle Scholar
Elmstrθøm, R, Lassen, PB and Larsen, PG 1994. “The IFAD VDM-SL toolbox: a practical approach to formal specificationsACM SIGPLAN Notices 29(9).Google Scholar
Elmstrθøm, R, Lintulampi, R and Pezze, M, 1993. “Giving semantics to SA/RT by means of high level timed Petri netsReal-Time Systems 5(2–3).Google Scholar
Feijs, LMG and Jonkers, HBM, 1992. Formal Specification and Design, Cambridge Tracts in Theoretical Computer Science, no 35, Cambridge University Press.Google Scholar
Feijs, LMG, Jonkers, HBM, Koymans, CPJ and Renardel de Lavalette, GR, 1989. Formal definition of the design language COLD-K (Preliminary version), ESPRIT document METEOR/t7/PRLE/7, 04 1987 (Final version: 08 1989).Google Scholar
Fensel, D, 1995. The Knowledge Acquisition and Representation Language KARL, Kluwer.CrossRefGoogle Scholar
Fensel, C, Angele, I, Landes, D and Studer, R, 1993. “Giving structured analysis techniques a formal and operational semantics with KARL” In: Züllighoven, H et al. , eds., Requirements Engineering '93: Prototyping, Teubner Verlag.Google Scholar
Fensel, D and van, Harmelen F, 1994. “A comparison of languages with operationalize and formalize KADS models of expertiseThe Knowledge Engineering Review 9(2).Google Scholar
Fensel, D and Neubert, S, 1994. “Integration of semiformal and formal methods for specification of knowledge-based systems” In: Wolfinger, B, ed., Innovation bei Rechen- und Kommunikationssystemen, Informatik Aktuell, Springer-Verlag.Google Scholar
France, RB and Docker, TWG, 1989. “Formal specifications using structured system analysis” In: Proceedings of the 2nd European Software Conference ESEC'89 Warwick, 09 11–15, Lecture Notes in Computer Science, no 387, Springer-Verlag.Google Scholar
Fuchs, NE, 1992. “Specifications are (preferably) executableSoftware Engineering Journal 7.Google Scholar
Futatsugi, K, Goguen, JA, Jouannaud, JP and Meseguer, J, 1985. “Principles of OBJ2” In: Proceedings of the 12th ACM Symposium on Principles of Programming Languages, New Orleans, LA.Google Scholar
Gaudel, MC, 1984. A First Introduction to PLUSS Technical report, LRI, Universite Paris Sud, Orsay.Google Scholar
Gaudel, MC, 1990. “Algebraic specifications” In: McDermied, J, ed., Software Engineer's Reference, Butterworth.Google Scholar
Gaudel, MC, 1994. “Formal specification techniques In: Proceedings of the 16th International Conference on Software Engineering (ICSE-94)May 16–21,Sorrento, Italy.Google Scholar
Gavrila, I and Treur, J, 1993. “A formal model for the dynamics of compositional reasoning systems In: Proceedings of the 11th European Conference on Artificial Intelligence (ECAI-94) Amsterdam, The Netherlands, 08 8–12. (An extended version is available as research report, no IR-323, Vrije Universiteit Amsterdam.)Google Scholar
Geelen, P, Ruttkay, Z and Treur, J, 1991. Logical Analysis and Specification of an Office Assignment Task research report, no IR-283, Vrije Universiteit Amsterdam.Google Scholar
Gerrard, CP, Coleman, D and Gallimore, M, 1990. “Formal specification and design time testing IEEE Transactions on Software Engineering 16(1).Google Scholar
Groenboom, R and Renardel de Lavalette, G, 1994. “Reasoning about dynamic features in specification languages” In: Andrews, DJ et al. , eds., Semantics of Specification Languages, Springer-Verlag.Google Scholar
Groenboom, R and Renardel, de Lavalette G, 1995. “A formalisation for evolving algebra” In: Proceedings of Accolade 95, Dutch Graduate School in Logic, Amsterdam.Google Scholar
Gurevich, Y, 1993. Evolving Algebras. A Tutorial Introduction In: Rozenberg, G et al. , eds., Current Trends in Theoretical Computer Science, World Scientific.Google Scholar
Gurevich, Y, 1994. “Evolving algebras 1993; Lipari guide” In: Börger, EB, eds., Specification and Validation Methods, Oxford Univesrsity Press.Google Scholar
Harel, D, 1984. “Dynamic logic In: Gabby, D et al. , eds., Handbook of Philosophical Logic, vol. II, Extensions of Classical Logic, Kluwer.Google Scholar
van Harmelen, F and Balder, J, 1992. “(ML)2: a formal language for KADS conceptual modelsKnowledge Acquisition 4(1).CrossRefGoogle Scholar
van Harmelen, F and Fensel, D, 1995. “Formal methods in knowledge engineeringThe Knowledge Engineering Review 10(4).Google Scholar
Hasselbring, W, 1994. Prototyping Parallel Algorithms in a Set-Oriented Language, Verlag Dr. Kovac, Hamburg, Germany.Google Scholar
Hayes, IJ, 1992. “VDM and Z: a comparative case studyFormalAspects of Computing 4(1).Google Scholar
Hayes, IJ and Jones, CB, 1989. “Specifications are not (necessarily) executableSoftware Engineering Journal 4(6).Google Scholar
Hayes, IJ, Jones, CB and Nicholls, JE, 1994. “Understanding the difference between VDM and ZACM Sigsoft Software Engineering Notes 19(3).Google Scholar
He, X, 1995. “PZ Nets—a formal method integrating Petri nets with Z” In: Proceedings of the 7th International Conference on Software Engineering and Knowledge Engineering (SEKE-95) Rockville, MD, 06 22–24.Google Scholar
Huggins, JK, 1993. Evolving Algebra Interpreter, Manuscript University of Michican.Google Scholar
Jones, CB, 1990. Systematic Software Development Using VDM, 2nd ed, Prentice Hall.Google Scholar
Jungclaus, R, 1993. Modeling of Dynamic Object Systems—A Logic-based Approach, Vieweg Verlag.Google Scholar
Kappel, AM, 1993. “Executable specifications based on dynamic algebras” In: Proceedings of the 4th International Conference on Logic Programming and Automated Reasoning (LPAR-93) St Petersburg, Russia, 07 13–20.Google Scholar
Karbach, W and Voβ, A, 1993. “MODEL-K for prototyping and strategic reasoning at the knowledge level” In: David, M et al. , eds., Second Generation Expert Systems, Springer-Verlag.Google Scholar
Kifer, M, Lausen, G and Wu, J, 1993. Logical Foundations of Object-Oriented and Frame-Based Languages. In: Technical Report 93/06, Department of Computer Science, SUNY at Stony Brook, NY. (To appear in Journal of the ACM.)Google Scholar
Kozen, D, 1990. “Logics of programs In: Leeuwen, J v, ed., Handbook of Theoretical Computer Science, Elsevier.Google Scholar
Krause, P, Fox, J, O'Neill, M and Glowinski, A, 1993. “Can we formally specify a medical decision support systems IEEE Expert 8(3).Google Scholar
van Langevelde, I, Philipsen, A and Treur, J, 1992. “Formal specification of compositional architectures In: Proceedings of the 10th European Conference on Artificial Intelligence (ECAI-92) Vienna, Austria, 08 3–7. (An extended version is available as research report, no IR-282, Vrije Universiteit Amsterdam.)Google Scholar
van, Langevelde I, Philipse, A and Treur, J, 1993. “A compositional architecture for simple design formally specified in DESIRE In: Treur, J and Wetter, Th, eds., Formal Specification of Complex Reasoning Systems, Ellis Horwood.Google Scholar
Larsen, PG, van Katwijk, J, Plat, N, Pronk, K and Toetenel, H, 1991. “SVDM: An integrated combination of SA and VDM In: Proceedings of the Methods Integration Conference, Leeds, UK.Google Scholar
Larsen, PG, Plat, N and Toetenel, H, 1993.“A formal semantics of data flow diagramsFormal Aspects of Computing 3.Google Scholar
Lassen, PB and Larsen, PG, 1991. “An executable subset of Meta-IV with loose specification” In: Proceedings of the VDM'91 Formal Software Development Methods, Noordwijkerhout, The Netherlands, 10, Springer-Verlag.Google Scholar
Linster, M, 1992. Knowledge Acquisition Based on Explicit Methods of Problem Solving PhD dissertation, University of Kaiserslautern.Google Scholar
Marcus, S, ed., 1988. Automating Knowledge Acquisition for Experts Systems, Kluwer.Google Scholar
McDermott, J, 1982. “Ri: A rule-based configurer of computer systems Artificial Intelligence 19.Google Scholar
Milnes, BG, 1992. A Specification of the Soar Cognitive Architecture in Z, Research report CMU-CS-92–169, School of Computer Science, Carnegie Mellon University, Pittsburg, PA.Google Scholar
Nakagawa, AT, Sakakihara, T and Futatsugi, K, 1993. “Algebraic specification of reasoning systems” In: Treur, J and Wetter, Th, eds., Formal Specification of Complex Reasoning Systems, Ellis Horwood.Google Scholar
Newell, A, 1982. “The knowledge levelArtificial Intelligence 18.Google Scholar
Oberweis, A, Scherrer, G and Stucky, W, 1994. “INCOME/STAR: methodology and tools for the development of distributed information systemsInformation Systems 19(8).Google Scholar
Pierret-Golbreich, C and Talon, X, 1995. “An algebraic specification of the dynamic behaviour of knowledge- based systems” The Knowledge Engineering Review (submitted).CrossRefGoogle Scholar
Plotkin, GD, 1981. A Structural Approach to Operational Semantics, Technical report, no DAIMI FN-19, Aaarhus University, Denmark.Google Scholar
Przymusinski, TC, 1988. “On the declarative semantics of deductive databases and logic programs” In: Minker, J, ed., Foundations of Deductive Databases and Logic Programming, Morgan Kaufmann.Google Scholar
Randell, GP, 1990. Translating Data Flow Diagrams into Z (and Vice Versa), Technical Report 90019, Procurement Executive, Ministry of Defence, RSRE, Malvern, Worcestershire, UK.Google Scholar
Ross, DT, 1977. “Structured analysis (SA): a language for communicating ideasIEEE Transactions on Software Engineering 3(1).Google Scholar
Rumbaugh, J, Blaha, M, Premerlani, W, Eddy, F and Lorensen, W, 1991. Object-Oriented Modelling and Design, Prentice-Hall.Google Scholar
Ryan, P and Sennett, C, 1993. Formal Methods in Systems Engineering, Springer-Verlag.Google Scholar
Schreiber, ATh, 1992. Pragmatics of the Knowledge Level, PhD dissertation, University of Amsterdam.Google Scholar
Schreiber, ATh and Birmingham, B, eds., 1995. Special issue on the VTSisyphus Task, International Journal of Human-Computer Studies (IJHCS) (in press).Google Scholar
Schreiber, ATh, Wielinga, BJ, Akkermans, H, Van, de Velde W and de, Hoog R, 1994. “CommonKADS. A comprchensive methodology for KBS development. IEEE Expert 9(6).CrossRefGoogle Scholar
Schreiber, ATh, Wielinga, BJ and Breuker, J, eds., 1993. KADS. A Principal Approach to Knowledge-Based System Development, Academic Press.Google Scholar
Schreiber, ATh, Wielinga, BJ and Jansweijer, W, 1995. “The KACTUS View on the ‘O’ Word” In: Proceedings of the Dutch National Conference on Al (NAIC-95) Rotterdam.Google Scholar
Schwarz, JT, Dewar, R, Dubinski, E and Schonberg, E, 1986. Programming with Sets: An Introduction to SETL, Springer-Verlag.Google Scholar
Semmens, LT, France, RB and Docker, TWG, 1992. “Integrated structured analysis and formal specification techniquesThe Computer Journal 35(6).Google Scholar
Sernadas, A, Sernadas, C and Costa, JF, 1992. Object Specification Logic, Research Report INESC/DMIST, University of Lisbon. (To appear in Journal of Logic and Computation).Google Scholar
Sheppard, D, 1995. An Introduction to Formal Specification with Z and VDM, McGraw-Hill.Google Scholar
Spee, JW and in't Veld, L, 1994. “The Semantics of KBSSF: A language for KBS designKnowledge Acquisition 6(4).CrossRefGoogle Scholar
Spivey, JM, 1988. Understanding Z. A Specification Language and its Formal Semantics, Cambridge University Press.Google Scholar
Spivey, JM, 1992. The Z Notation. A Reference Manual, 2nd ed. Prentice Hall.Google Scholar
Spruit, PA, Wieringa, RJ and Meyer, J-JC, 1993. “Dynamic database logic: the first-order case” In: Lipeck, UW et al. , eds., Modelling Database Dynamics Springer-Verlag.Google Scholar
Spruit, PA, Wieringa, RJ and Meyer, J-JC, 1995. “Axiomatization, declarative semantics and operational semantics of passive and active updates in logic databasesJournal of Logic Computation 5(1).Google Scholar
Stepney, S., Barden, Rand Cooper D, eds., 1992. Object Orientation in Z, Springer-Verlag.Google Scholar
Treur, J, 1992. “Interaction types and chemistry of generic task models” In: Linster, M et al. , eds., Proceedings of the European Knowledge Acquisition Workshop (EKAW-91) GMD Studien, no 211.Google Scholar
Treur, J, 1994. “Temporal semantics of meta-level architectures for dynamic control of reasoning” In: Fribourg, L et al. , eds., Logic Program Synthesis and Transformation—Meta Programming in Logic, Proceedings of the 4th International Workshops, LOPSTER-94 and META-94, Pisa, Italy, 06 20–21 Lecture Notes in Computer Science, no, 883, Springer-Verlag.Google Scholar
Treur, J and Wetter, Th, eds., 1993. Formal Specification of Complex Reasoning Systems, Ellis Horwood.Google Scholar
Turner, JG and McCluskey, TL, 1994. The Construction of Formal Specifications, McGraw-Hill.Google Scholar
Veld, L, Jonker, W and Spec, JW, 1993. “The specification of complex reasoning tasks in KBSSF” In: Treur, J and Wetter, Th, eds., Formal Specification of Complex Reasoning Systems, Ellis Horwood.Google Scholar
Voss, H and Voss, A, 1993. “Reuse-oriented knowledge engineering with MoMo” In: Proceedings of the 5th International Conference on Software Engineering and Knowledge Engineering (SEKE93) San Francisco Bay, 06 14–18.Google Scholar
Wielinga, BJ and Schreiber, ATh, 1994. “Conceptual modeling of large reusable knowledge bases”. In: von Luck, K et al. , eds., Management and Processing of Complex Data Structures Lecture Notes in Computer Science, no 777, Springer-Verlag.Google Scholar
Wielinga, BJ, Schreiber, ATh and Breuker, JA, 1992. “KADS: A modelling approach to knowledge engineeringKnowledge Acquisition 4(1).Google Scholar
Wieringa, RJ, 1991a. “A formalization of objects using equational dynamic logic” In: Proceedings of the 2nd International Conference on Deductive and Object-Oriented Databases (DOOD-91) Munich, Germany, 12 16–18, Springer-Verlag.Google Scholar
Wieringa, RJ, 1991b. “Steps towards a method for the formal modeling of dynamic objectsData and Knowledge Engineering 6.Google Scholar
Wieringa, RJ and van, de Riet RP, 1990. “Algebraic specification of object dynamics in knowledge based domains” In: Meersman, RA et al. , eds., Artificial Intelligence Databases and Information Systems (DS-3), North-Holland.Google Scholar
Wirsing, M, 1990. “Algebraic specification” In: van Leeuwen, J, ed., Handbook of Theoretical Computer Science, Elsevier.Google Scholar
Wood, KR, 1993, “A practical approach to software engineering using Z and the refinement calculus” In: Proceedings of the First ACM SIGSOFT Symposium on the Foundation of Software Engineering Los Angeles, CA, 12 7–10, ACM Software Engineering Notes 18(5).Google Scholar
Woodcock, JCP and Larsen, PG, eds., 1993. “FME'93: Industrial strength formal methods” Proceedings of the First International Symposium of Formal Methods Europe Odense, Denmark, 04 19–23; Lecture Notes in Computer Science, no 670, Springer-Verlag.Google Scholar
Wordsworth, JB, 1992. Software Development with Z, Addison-Wesley.Google Scholar
Yourdon, E, 1989. Modern Structured Analysis, Prentice-Hall.Google Scholar
Zave, P, 1982. “An operational approach to requirements specification for embedded systemsIEEE Transactions on Software Engineering 3(8).Google Scholar
Zave, P, 1991. “An insider's evaluation of PAISleyIEEE Transactions on Software Engineering 17(3).Google Scholar