Ragnhild Kobro Runde

• Runde, Ragnhild Kobro; Cutts, Quintin & Skaarseth, Lars Kristian (2023). Exploring Scratch to Python Transfer in Norwegian Lower Secondary Schools. NIKT: Norsk IKT-konferanse for forskning og utdanning. ISSN 1892-0713. Full text in Research Archive
• Cutts, Quintin; Kallia, Maria; Anderson, Ruth; Crick, Tom; Devlin, Marie & Farghally, Mohammad [Show all 11 contributors for this article] (2023). Considering Computing Education in Undergraduate Computer Science Programmes. In Laakso, Mikko-Jussi; Monga, Mattia; Simon, - & Sheard, Judy (Ed.), ITiCSE 2023: Proceedings of the 2023 Conference on Innovation and Technology in Computer Science Education. Association for Computing Machinery (ACM). ISSN 9798400701399. p. 567–568. doi: 10.1145/3587103.3594210. Full text in Research Archive
• Cutts, Quintin; Kallia, Maria; Anderson, Ruth; Crick, Tom; Devlin, Marie & Farghally, Mohammad [Show all 11 contributors for this article] (2023). Arguments for and Approaches to Computing Education in Undergraduate Computer Science Programmes. In Laakso, Mikko-Jussi; Monga, Mattia; Simon, - & Sheard, Judy (Ed.), ITiCSE-WGR '23: Proceedings of the 2023 Working Group Reports on Innovation and Technology in Computer Science Education. Association for Computing Machinery (ACM). ISSN 9798400704055. p. 160–195. doi: 10.1145/3623762.3633494. Full text in Research Archive
• Radišić, Jelena; Nortvedt, Guri A. & Runde, Ragnhild Kobro (2022). Relationships Between Mathematics Self-Belief: Exposure to ICT in School and Achievement on PISA 2012 Paper and Computer-Based Mathematics Assessment. In Martin, Christie; Miller, Bridget T & Polly, Drew (Ed.), Technology Integration and Transformation in STEM Classrooms. IGI Global. ISSN 9781668459201. doi: 10.4018/978-1-6684-5920-1.ch012. Full text in Research Archive Show summary

  This chapter discussed the relationships between students' self-beliefs and interest in mathematics, their exposure to ICT in school and mathematics lessons, and their achievement levels. The authors linked data from the PISA 2012, comprising both paper- and computer-based mathematics assessments to data from student questionnaires for 16 European countries participating in both assessment formats. LPA was applied to identify and distinguish between six student groups. The results indicated that self-beliefs were more strongly related to achievement than the level of ICT use was. Students with the highest reported self-beliefs and moderate ICT exposure outscored other students. The same patterns were observed for both assessment formats. For most of the countries observed, nearly 50% of the students were characterized by average self-beliefs and low or no use of ICT. On average, these students had achievement scores close to the OECD mean. Across all countries, students with low self-beliefs also had the lowest average achievement scores, regardless of their extent of exposure to ICT.

• Rørnes, Kristin Marie; Runde, Ragnhild Kobro & Jensen, Siri Moe (2019). Students’ mental models of references in Python. NIKT: Norsk IKT-konferanse for forskning og utdanning. ISSN 1892-0713. Full text in Research Archive
• Refsdal, Atle; Runde, Ragnhild Kobro & Stølen, Ketil (2016). Mandatory and Potential Choice: Comparing Event-B and STAIRS. In Petre, Luigia & Sekerinski, Emil (Ed.), From Action Systems to Distributed Systems: The Refinement Approach. CRC Press. ISSN 9781498701587. p. 15–27. doi: 10.1201/b20053-4. Full text in Research Archive Show summary

  In order to decide whether a software system fulfills a specification, or whether a detailed specification preserves the properties of a more abstract specification, we need an understanding of what it means for one specification to fulfill another specification. This is particularly important when the specification contains one or more operators for expressing choice. Operators for choice have been studied for more than three decades within the field of formal methods in general, and within methods for action-refinement in particular. In this paper we focus on Event-B, a more recent method for action refinement. The STAIRS method belongs to another tradition. It originates from the UML community and is designed to provide an understanding of refinement and fulfillment for UML. STAIRS distinguishes between potential and mandatory choice, where only the latter is required to by preserved by refinement. This paper investigates the relationship between the operators for choice in Event-B and STAIRS.

• Andresen, Kjetil; Møller-Pedersen, Birger & Runde, Ragnhild Kobro (2015). Combined Modelling and Programming Support for Composite States and Extensible State Machines. In Hammoudi, Slimane; Pires, Luis Ferreira; Desfray, Philippe & Filipe, Joaquim (Ed.), MODELSWARD 2015 - Proceedings of the 3rd International Conference on Model-Driven Engineering and Software Development, ESEO, Angers, Loire Valley, France, 9-11 February, 2015. SciTePress. ISSN 9789897580833. p. 231–238. doi: 10.5220/0005237302310238. Full text in Research Archive
• Refsdal, Atle; Runde, Ragnhild Kobro & Stølen, Ketil (2015). Stepwise refinement of sequence diagrams with soft real-time constraints. Journal of computer and system sciences. ISSN 0022-0000. 81(7), p. 1221–1251. doi: 10.1016/j.jcss.2015.03.003. Full text in Research Archive Show summary

  UML sequence diagrams and similar notations are much used to specify and analyze computer systems and their requirements. Probabilities are often essential, in particular for capturing soft real-time constraints. It is also important to be able to specify systems at different levels of abstraction. Refinement is a means to relate abstract specifications to more concrete specifications in such a way that constraints and analysis results are preserved through the transition. In order to allow soft real-time constraints to be included as an integral part of sequence diagram specifications, this paper presents an approach to extend UML 2.x sequence diagrams to capture probabilistic choice in general and soft real-time constraints in particular. The approach is supported by formal semantics and pragmatic refinement relations with mathematical properties that allow stepwise and modular development of specifications. An example focusing on communication is provided to demonstrate the language and refinement relations.

• Erdogan, Gencer; Li, Yan; Runde, Ragnhild Kobro; Seehusen, Fredrik & Stølen, Ketil (2014). Approaches for the combined use of risk analysis and testing: A systematic literature review. International Journal on Software Tools for Technology Transfer (STTT). ISSN 1433-2779. 16(5), p. 627–642. doi: 10.1007/s10009-014-0330-5. Full text in Research Archive Show summary

  Risk analysis and testing are conducted for different purposes. Risk analysis and testing nevertheless involve processes that may be combined to the benefit of both. We may use testing to support risk analysis and risk analysis to support testing. This paper surveys literature on the combined use of risk analysis and testing. First, the existing approaches are identified through a systematic literature review. The identified approaches are then classified and discussed with respect to main goal, context of use and maturity level. The survey highlights the need for more structure and rigor in the definition and presentation of approaches. Evaluations are missing in most cases. The paper may serve as a basis for examining approaches for the combined use of risk analysis and testing, or as a resource for identifying the adequate approach to use.

• Runde, Ragnhild Kobro; Refsdal, Atle & Stølen, Ketil (2013). Relating computer systems to sequence diagrams: the impact of underspecification and inherent nondeterminism. Formal Aspects of Computing. ISSN 0934-5043. 25(2), p. 159–187. doi: 10.1007/s00165-011-0192-5. Full text in Research Archive Show summary

  Having a sequence diagram specification and a computer system, we need to answer the question: Is the system compliant with the sequence diagram specification in the desired way? We present a procedure for answering this question for sequence diagrams with underspecification and inherent nondeterminism. The procedure is independent of any concrete technology, and relies only on the execution traces that may be produced by the system. If all traces are known, the procedure results in either “compliant” or “not compliant”. If only a subset of the traces is known, the conclusion may also be “likely compliant” or “likely not compliant”.

• Grønmo, Roy; Runde, Ragnhild Kobro & Møller-Pedersen, Birger (2013). Confluence of aspects for sequence diagrams. Software and Systems Modeling (SoSyM). ISSN 1619-1366. 12(4), p. 789–824. doi: 10.1007/s10270-011-0212-1. Full text in Research Archive Show summary

  The last decade has seen several aspect language proposals for UML 2 sequence diagrams. Aspects allow the modeler to define crosscutting concerns of sequence diagrams and to have these woven with the sequence diagrams of a so-called base model, in order to create a woven model. In a real-world scenario, there may be multiple aspects applicable to the same base model. This raises the need to analyse the set of aspects to identify possible aspect interactions (dependencies and conflicts) between applications of aspects. We call a set of aspects terminating if they may not be applied infinitely many times for any given base model. Furthermore, we call a set of terminating aspects confluent, if they, for any given base model, always yield the same final result regardless of the order in which they are applied. Since confluence must hold for any base model, this is a much stronger result than many of the current approaches that have addressed detection of aspect interactions limited to a specific base model. Our aspects are specified using standard sequence diagrams with some extensions. In this paper, we present a confluence theory specialized for our highly expressive aspect language. For the most expressive aspects, we prove that confluence is undecidable. For another class of aspects with considerable expressiveness, we prescribe an algorithm to check confluence. This algorithm is based on what we call an extended critical pair analysis. These results are useful both for modelers and researchers working with sequence diagram aspects and for researchers wanting to establish a confluence theory for other aspect-oriented modelling or model transformation approaches.

• Li, Yan; Runde, Ragnhild Kobro & Stølen, Ketil (2013). Towards a pattern language for security risk analysis of web applications. In Köppe, Christian (Eds.), PLoP 2013 Conference Proceedings, 20th Conference on pattern languages and programs. Hillside. ISSN 9781941652008. Full text in Research Archive Show summary

  This article introduces a pattern language for security risk analysis of web applications in an example driven manner. The example patterns presented include a composite pattern and three basic patterns, namely a security requirements pattern, a web application design pattern and a risk analysis modelling pattern. The pattern language is intended to be used as a guideline to capture the security risk picture of a web application, especially in the early phase of the software development life cycle. The overall aim is to support light weighted security risk analysis for web applications.

• Rossebø, Judith Ellen Yarranton & Runde, Ragnhild Kobro (2011). How to Model Dynamic Service Composition Using UML 2.x and Composition Policies. In Ahson, Syed A. & Ilyas, Mohammad (Ed.), Service Delivery Platforms: Developing and Deploying Converged Multimedia Services. CRC Press. ISSN 9781439800898. p. 87–122. doi: 10.1007/978-3-540-87875-9_37. Full text in Research Archive
• Haugen, Øystein & Runde, Ragnhild Kobro (2009). Enhancing UML to Formalize the FIPA Agent Interaction Protocol. Lecture Notes in Business Information Processing. ISSN 1865-1348. 25, p. 154–173. Full text in Research Archive
• Rossebø, Judith Ellen Yarranton & Runde, Ragnhild Kobro (2009). Methodology for Model-Based Dynamic Composition of Services. In Aalberg, Trond (Eds.), Norsk informatikkonferanse NIK 2009. Tapir Akademisk Forlag. ISSN 9788251924917. p. 1–12. Full text in Research Archive
• Rossebø, Judith Ellen Yarranton & Runde, Ragnhild Kobro (2008). Specifying Service Composition Using UML 2.x and Composition Policies. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 5301, p. 520–536. Full text in Research Archive
• Halvorsen, Oddleif; Runde, Ragnhild Kobro & Haugen, Øystein (2007). Time Exceptions in Sequence Diagrams. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 4364, p. 131–142. Full text in Research Archive
• Refsdal, Atle; Runde, Ragnhild Kobro & Stølen, Ketil (2006). Underspecification, inherent nondeterminism and probability in sequence diagrams. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 4037, p. 138–155. Full text in Research Archive
• Runde, Ragnhild Kobro; Haugen, Øystein & Stølen, Ketil (2006). The pragmatics of STAIRS. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 4111, p. 88–114. Full text in Research Archive
• Halvorsen, Oddleif; Runde, Ragnhild Kobro & Haugen, Øystein (2006). Time Exceptions in Sequence Diagrams. In Gerard, Sebastien; Graf, S; Haugen, Øystein; Ober, I & Selic, Bran (Ed.), MARTES 2006 at MoDELS 2006 - International workshop on Modeling and Analysis of Real-Time and Embedded Systems. Universitetet i Oslo. ISSN 9788273682994. p. 81–100. Full text in Research Archive
• Runde, Ragnhild Kobro; Haugen, Øystein & Stølen, Ketil (2005). Refining UML interactions with underspecification and nondeterminism. Nordic Journal of Computing. ISSN 1236-6064. 12(2), p. 157–188. Full text in Research Archive
• Haugen, Øystein; Husa, Knut Eilif; Runde, Ragnhild Kobro & Stølen, Ketil (2005). Why timed sequence diagrams require three-event semantics. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 3466, p. 1–25. Full text in Research Archive
• Haugen, Øystein; Husa, Knut Eilif; Runde, Ragnhild Kobro & Stølen, Ketil (2005). STAIRS towards formal design with sequence diagrams. Software and Systems Modeling (SoSyM). ISSN 1619-1366. 4(4), p. 355–367. Full text in Research Archive
• Runde, Ragnhild Kobro; Haugen, Øystein & Stølen, Ketil (2005). How to transform UML neg into a useful construct. In Coward, Eivind (Eds.), Norsk informatikkonferanse NIK'2005. Tapir Akademisk Forlag. ISSN 9788251920810. p. 55–66. Full text in Research Archive

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• Bjørndalen, John Markus; Bongo, Lars Ailo; Haugland, Dag; Hjelmås, Erik; Løkketangen, Arne & Møller-Pedersen, Birger [Show all 10 contributors for this article] (2011). Norsk Informatikkonferanse NIK 2011. Tapir Akademisk Forlag. ISBN 9788251928434. 262 p. Full text in Research Archive
• Bjørndalen, John Markus; Haugland, Dag; Hjelmås, Erik; Løkketangen, Arne; Møller-Pedersen, Birger & Prinz, Andreas [Show all 9 contributors for this article] (2009). Norsk informatikkonferanse : NIK 2009 : Institutt for datateknikk og informasjonsvitenskap, NTNU, 23.-25. november 2009. Tapir Akademisk Forlag. ISBN 9788251924917. 170 p. Full text in Research Archive

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• Mørken, Knut Martin; Runde, Ragnhild Kobro & Skramstad, Tone (2017). Det nasjonale kvalifikasjonsrammeverket og utdanningsutvikling. Full text in Research Archive
• Møller-Pedersen, Birger & Runde, Ragnhild Kobro (2016). State Pattern supporting both composite States and extension/specialization of State Machines. Full text in Research Archive
• Rossebø, Judith Ellen Yarranton & Runde, Ragnhild Kobro (2009). A Model-Based Approach to Dynamic Service Composition, Exemplified on Voice over IP. Telektronikk. ISSN 0085-7130. 105(1), p. 98–106. Full text in Research Archive
• Runde, Ragnhild Kobro & Aagedal, Jan Øyvind (2009). Guidelines for Developing Sequence Diagram Specifications, Exemplified for IPTV. Telektronikk. ISSN 0085-7130. 105(1), p. 59–68. Full text in Research Archive
• Stølen, Ketil & Runde, Ragnhild Kobro (2009). Guest Editorial: Model-Driven Security - Integrating Availability in System Development. Telektronikk. ISSN 0085-7130. 105(1), p. 1–2. Full text in Research Archive
• Runde, Ragnhild Kobro (2005). UpSTAIRS with Sequence Diagrams. Full text in Research Archive
• Runde, Ragnhild Kobro (2005). UML neg - nyttig eller ubrukelig? Full text in Research Archive
• Runde, Ragnhild Kobro (2004). Refining UML interactions. Full text in Research Archive
• Johnsen, Einar Broch; Owe, Olaf & Runde, Ragnhild Kobro (2001). The Oslo School on Formalization of Distributed Systems. Full text in Research Archive
• Runde, Ragnhild Kobro & Owe, Olaf (2000). Forenklet, men presis beskrivelse av objekter. Full text in Research Archive
• Runde, Ragnhild Kobro (2000). Towards intuitive specifications with ready relations. Full text in Research Archive
• Erdogan, Gencer; Li, Yan; Runde, Ragnhild Kobro; Seehusen, Fredrik & Stølen, Ketil (2012). Conceptual Framework for the DIAMONDS Project. SINTEF Digital. ISSN 9788214052886. Full text in Research Archive Show summary

  DIAMONDS is a research project addressing the combination of security testing and risk analysis. The main objective is to develop guidelines and a supporting framework to help businesses find a balanced approach within the three-dimensional space of invested effort, security testing, and risk analysis. This report documents the conceptual framework for DIAMONDS by clarifying the notions of security testing, risk analysis, and related notions, as well as defining the relations among them. Oppdragsgiver: The DIAMONDS project supported by the Research Council of Norway

• Refsdal, Atle; Runde, Ragnhild Kobro & Stølen, Ketil (2011). Stepwise refinement of sequence diagrams with soft real-time requirements. SINTEF Digital. ISSN 9788214049855. Full text in Research Archive Show summary

  UML sequence diagrams and similar notations are much used to specify computer systems, serving for example as specifications for programmers, or as a means for validating requirements. When specifying and analyzing computer systems, probabilities are often essential, in particular for capturing soft real-time requirements. It is also important to be able to specify systems at different levels of abstraction, depending on how far the development has progressed and the purpose of the specification. Refinement is a means to relate abstract specifications to more concrete specifications in such a way that requirements and analysis results are preserved through the transition from the abstract to the more concrete level. This paper presents an approach to extend UML 2.x sequence diagrams to capture probabilistic choice in general and soft real-time requirements in particular. The approach is supported by formal semantics and pragmatic refinement relations. The refinement relations have mathematical properties that allow specifications to be developed in a stepwise and modular manner. An example focusing on communication is provided to demonstrate the use and usefulness of the language and the refinement relations Oppdragsgiver: Research Council of Norway

• Halvorsen, Oddleif; Runde, Ragnhild Kobro & Haugen, Øystein (2008). Time exceptions in sequence diagrams. Universitetet i Oslo. Full text in Research Archive Show summary

  UML sequence diagrams partially describe a system. We show how the description may be augmented with exceptions triggered by the violation of timing constraints and compare our approach to those of the UML 2.1 simple time model, the UML Testing Profile and the UML profile for Schedulability, Performance and Time. We give a formal definition of time exceptions in sequence diagrams and show that the concepts are compositional. An ATM example is used to explain and motivate the concepts.

• Runde, Ragnhild Kobro; Haugen, Øystein & Stølen, Ketil (2007). The pragmatics of STAIRS. Universitetet i Oslo. Full text in Research Archive Show summary

  STAIRS is a method for the compositional development of interactions in the setting of UML 2.0. In addition to defining denotational trace semantics for the main aspects of interactions, STAIRS focuses on how interactions may be developed through successive refinement steps. In this tutorial paper, we concentrate on explaining the practical relevance of STAIRS. Guidelines are given on how to create interactions using the different STAIRS operators, and how these may be refined. The pragmatics is illustrated by a running example.

• Refsdal, Atle; Runde, Ragnhild Kobro & Stølen, Ketil (2007). Relating computer systems to sequence diagrams with underspecification, inherent nondeterminism and probabilistic choice : Part 2. Universitetet i Oslo. Full text in Research Archive Show summary

  Having a sequence diagram specification and a computer system, we need to answer the question: Is the system compliant with the sequence diagram specification in the desired way? We present a procedure for answering this question for three variations of sequence diagrams. The procedure does not require access to information about the internals of the system such as program code. The semantics of sequence diagrams is denotational and based on traces. In order to answer the initial question, the procedure starts by obtaining a basic representation of the system by e.g. testing.This representation is then transformed into the same semantic model as that used for the sequence diagram. Finally, a formal definition of compliance is applied to determine whether the system complies with the specification. Compliance is closely related to refinement, and the definitions of compliance are based on refinement definitions. Therefore refinement as well as compliance is addressed. Compliance is not identical to refinement due to the partial nature of sequence diagram specifications. The work is split in two parts. Part 1 [RRS07] introduces the necessary definitions for using the compliance checking procedure on sequence diagrams with underspecification and sequence diagrams with inherent nondeterminism. This paper presents Part 2, in which we introduce the necessary definitions for using the compliance checking procedure on sequence diagrams with probabilistic choice. Part 1 is a necessary prerequisite for Part 2.

• Runde, Ragnhild Kobro; Haugen, Øystein & Stølen, Ketil (2007). Refining UML interactions with underspecification and nondeterminism. Universitetet i Oslo. Full text in Research Archive Show summary

  STAIRS is an approach to the compositional development of UML interactions, such as sequence diagrams and interaction overview diagrams. An important aspect of STAIRS is the ability to distinguish between underspecification and inherent nondeterminism through the use of potential and mandatory alternatives. This paper investigates this distinction in more detail. Refinement notions explain when (and how) both kinds of nondeterminism may be reduced during the development process. In particular, in this paper we extend STAIRS with guards, which may be used to specify the choice between alternatives. Finally, we introduce the notion of an implementation and define what it means for an implementation to be correct with respect to a specification.

• Runde, Ragnhild Kobro (2007). STAIRS case study : the BuddySync system. Universitetet i Oslo. Full text in Research Archive Show summary

  This paper presents a case study evaluating the use of STAIRS when specifying a system for connecting service providers and people requesting those services. As part of the case study, we give an example of how STAIRS may be used in combination with development methodologies like e.g. RUP. We conclude that STAIRS seems a promising method for working with UML 2.x interactions, and indicate some possible directions for future research.

• Refsdal, Atle; Runde, Ragnhild Kobro & Stølen, Ketil (2007). Relating computer systems to sequence diagrams with underspecification, inherent nondeterminism and probabilistic choice. Part 2: probabilistic choice. Research Report 347. Universitetet i Oslo. ISSN 9788273683045. Full text in Research Archive Show summary

  Having a sequence diagram specification and a computer system, we need to answer the question: Is the system compliant with the sequence diagram specification in the desired way? We present a procedure for answering this question for three variations of sequence diagrams. The procedure does not require access to information about the internals of the system such as program code. The semantics of sequence diagrams is denotational and based on traces. In order to answer the initial question, the procedure starts by obtaining a basic representation of the system by e.g. testing. This representation is then transformed into the same semantic model as that used for the sequence diagram. Finally, a formal definition of compliance is applied to determine whether the system complies with the specification. Compliance is closely related to refinement, and the definitions of compliance are based on refinement definitions. Therefore refinement as well as compliance is addressed. Compliance is not identical to refinement due to the partial nature of sequence diagram specifications. The work is split in two parts. Part 1 [RRS07] introduces the necessary definitions for using the compliance checking procedure on sequence diagrams with underspecification and sequence diagrams with inherent nondeterminism. This paper presents Part 2, in which we introduce the necessary definitions for using the compliance checking procedure on sequence diagrams with probabilistic choice. Part 1 is a necessary prerequisite for Part 2.Having a sequence diagram specification and a computer system, we need to answer the question: Is the system compliant with the sequence diagram specification in the desired way? We present a procedure for answering this question for three variations of sequence diagrams. The procedure does not require access to information about the internals of the system such as program code. The semantics of sequence diagrams is denotational and based on traces. In order to answer the initial question, the procedure starts by obtaining a basic representation of the system by e.g. testing. This representation is then transformed into the same semantic model as that used for the sequence diagram. Finally, a formal definition of compliance is applied to determine whether the system complies with the specification. Compliance is closely related to refinement, and the definitions of compliance are based on refinement definitions. Therefore refinement as well as compliance is addressed. Compliance is not identical to refinement due to the partial nature of sequence diagram specifications. The work is split in two parts. Part 1 [RRS07] introduces the necessary definitions for using the compliance checking procedure on sequence diagrams with underspecification and sequence diagrams with inherent nondeterminism. This paper presents Part 2, in which we introduce the necessary definitions for using the compliance checking procedure on sequence diagrams with probabilistic choice. Part 1 is a necessary prerequisite for Part 2.

• Runde, Ragnhild Kobro (2007). STAIRS - Understanding and Developing Specifications Expressed as UML Interaction Diagrams. Universitetet i Oslo. Full text in Research Archive Show summary

  STAIRS is a method for the step-wise, compositional development of interactions in the setting of UML 2.x. UML 2.x interactions, such as sequence diagrams and interaction overview diagrams, are seen as intuitive ways of describing communication between different parts of a system, and between a system and its users. STAIRS addresses the challenges of harmonizing intuition and formal reasoning by providing a precise understanding of the partial nature of interactions, and of how this kind of incomplete specifications may be consistently refined into more complete specifications. For understanding individual interaction diagrams, STAIRS defines a denotational trace semantics for the main constructs of UML 2.x interactions. The semantic model takes into account the partiality of interactions, and the formal semantics of STAIRS is faithful to the informal semantics given in the UML 2.x standard. For developing UML 2.x interactions, STAIRS defines a number of refinement relations corresponding to basic system development steps. STAIRS also defines matching compliance relations, for relating interactions to real computer systems. An important feature of STAIRS is the distinction between underspecification and inherent nondeterminism. Underspecification means that there are several possible behaviours serving the same overall purpose, and that it is sufficient for a computer system to perform only one of these. On the other hand, inherent nondeterminism is used to capture alternative behaviours that must all be possible for an implementation. A typical example is the tossing of a coin, where both heads and tails should be possible outcomes. In some cases, using inherent nondeterminism may also be essential for ensuring the necessary security properties of a system.

• Refsdal, Atle; Runde, Ragnhild Kobro & Stølen, Ketil (2006). Underspecification, inherent nondeterminism and probability in sequence diagrams. Universitetet i Oslo. Full text in Research Archive Show summary

  Nondeterminism in specifications may be used for at least two different purposes. One is to express underspecification, which means that the specifier for the same environment behavior allows several alternative behaviors of the specified component and leaves the choice between these to those responsible for implementing the specification. In this case a valid implementation will need to implement at least one, but not necessarily all, alternatives. The other purpose is to express inherent nondeterminism, which means that a valid implementation needs to reflect all alternatives. STAIRS is an approach to the compositional and incremental development of sequence diagrams supporting underspecification as well as inherent nondeterminism. Probabilistic STAIRS builds on STAIRS and allows probabilities to be included in the specifications. Underspecification with respect to probabilities is also allowed. This paper investigates the use of underspecification, inherent nondeterminism and probability in sequence diagrams, the relationships between these concepts, and how these are expressed in STAIRS and probabilistic STAIRS.

• Runde, Ragnhild Kobro; Haugen, Øystein & Stølen, Ketil (2005). How to transform UML neg into a useful construct. Universitetet i Oslo. Full text in Research Archive Show summary

  In UML, the operator neg is used to specify negative, or unwanted, system behaviour. We agree that being able to specify negative behaviour is important. However, the UML neg is currently not wellsuited for this purpose, the main problem being that a single operator is used with several different meanings depending on the context. In this paper we investigate some alternative definitions of neg. We also propose a solution in which neg is replaced by two new operators for specifying negative behaviour.

• Haugen, Øystein; Husa, Knut Eilif; Runde, Ragnhild Kobro & Stølen, Ketil (2004). Why timed sequence diagrams require three-event semantics. Universitetet i Oslo. ISSN 9788273682611. Full text in Research Archive Show summary

  STAIRS is an approach to the compositional development of sequence diagrams supporting the specification of mandatory as well as potential behavior. In order to express the necessary distinction between black-box and glass-box refinement, an extension of the semantic framework with three event messages is introduced. A concrete syntax is also proposed. The proposed extension is especially useful when describing time constraints. The resulting approach, referred to as Timed STAIRS, is formally underpinned by denotational trace semantics. A trace is a sequence built from three kinds of events: events for transmission, reception and consumption. We argue that such traces give the necessary expressiveness to capture the standard UML interpretation of sequence diagrams as well as the black-box interpretation found in classical formal methods.

• Runde, Ragnhild Kobro & Stølen, Ketil (2003). What is Model Driven Architecture? Universitetet i Oslo. ISSN 9788273682567. Full text in Research Archive Show summary

  OMG promotes Model Driven Architecture (MDA) as the new direction for system development, especially supporting integration, interoperability and portability. But what is MDA really about, and what is model driven architecture? These are fundamental questions, to which precise answers are surprisingly hard to find. Not even the term "model driven" is clearly defined. This article views MDA as a framework for constructing methodologies for model driven development of system architectures. The exact meaning of this position is presented in detail, and a definition of the term "model driven" is proposed. The main concepts in MDA are explained, with an emphasis on giving specific guidelines as to which interpretation should be chosen in cases where the official documentation is ambiguous or unclear. In particular, the important notions of refinement and transformation are examined, and it is explained how these similar, but different, concepts are related. The conclusion gives a short survey describing to which extent current methodologies fulfil the visions of MDA, and points at important areas with a particular need for more research.

• Runde, Ragnhild Kobro (2000). Utprøving og forbedring av en formalisme for parallelle prosesser. IFI, UiO. Full text in Research Archive

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