Search results for "Requirements"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
20	Asarnusch Rashid	OpenProposal: Towards Collaborative End-User Participation in Requirements Management By Usage of Visual Requirement Specifications.	RE	2007	DBLP DOI BibTeX RDF
20	Mayumi Itakura Kamata, Tetsuo Tamai	How Does Requirements Quality Relate to Project Success or Failure?	RE	2007	DBLP DOI BibTeX RDF
20	Mikio Aoyama	Persona-Scenario-Goal Methodology for User-Centered Requirements Engineering.	RE	2007	DBLP DOI BibTeX RDF
20	Cornelius Ncube, James Lockerbie, Neil A. M. Maiden	Automatically Generating Requirements from i* Models: Experiences with a Complex Airport Operations System.	REFSQ	2007	DBLP DOI BibTeX RDF
20	Björn Regnell, Martin Höst, Richard Berntsson-Svensson	A Quality Performance Model for Cost-Benefit Analysis of Non-functional Requirements Applied to the Mobile Handset Domain.	REFSQ	2007	DBLP DOI BibTeX RDF
20	Lúcia R. D. Bastos, Jaelson Castro, John Mylopoulos	Deriving Architectures from Requirements.	RE	2006	DBLP DOI BibTeX RDF
20	Travis D. Breaux, Matthew W. Vail, Annie I. Antón	Towards Regulatory Compliance: Extracting Rights and Obligations to Align Requirements with Regulations.	RE	2006	DBLP DOI BibTeX RDF
20	Steven P. Miller	Proving the Shalls: Requirements, Proofs, and Model-Based Development.	RE	2006	DBLP DOI BibTeX RDF
20	Kun Chen, Wei Zhang 0004, Haiyan Zhao, Hong Mei 0001	An Approach to Constructing Feature Models Based on Requirements Clustering.	RE	2005	DBLP DOI BibTeX RDF
20	Neil A. M. Maiden, Suzanne Robertson	Integrating Creativity into Requirements Processes: Experiences with an Air Traffic Management System.	RE	2005	DBLP DOI BibTeX RDF
20	Kimberly S. Wasson, Kendra N. Schmid, Robyn R. Lutz, John C. Knight	Using Occurrence Properties of Defect Report Data to Improve Requirements.	RE	2005	DBLP DOI BibTeX RDF
20	Hung Tran Van, Axel van Lamsweerde, Philippe Massonet, Christophe Ponsard	Goal-Oriented Requirements Animation.	RE	2004	DBLP DOI BibTeX RDF
20	Bikram Sengupta, Rance Cleaveland	Refinement-Based Requirements Modeling Using TriggeredMessage Sequence Charts.	RE	2003	DBLP DOI BibTeX RDF
20	Alistair Mavin, Neil A. M. Maiden	Determining Socio-Technical Systems Requirements: Experiences with Generating and Walking through Scenarios.	RE	2003	DBLP DOI BibTeX RDF
20	Chi-Sheng Shih 0001, Jane W.-S. Liu	Acquiring and Incorporating State-Dependent Timing Requirements.	RE	2003	DBLP DOI BibTeX RDF
20	Andrés Silva	Requirements, domain and specifications: a viewpoint-based approach to requirements engineering.	ICSE	2002	DBLP DOI BibTeX RDF
20	Pascal Fenkam, Harald C. Gall, Mehdi Jazayeri	Visual Requirements Validation: Case Study in a Corba-Supported Environment.	RE	2002	DBLP DOI BibTeX RDF
20	Amador Durán 0001, Antonio Ruiz Cortés, Rafael Corchuelo, Miguel Toro	Supporting Requirements Verification Using XSLT.	RE	2002	DBLP DOI BibTeX RDF
20	Stewart A. Higgins, Maurice de Laat, Paul M. C. Gieles, Emilienne M. Geurts	Managing Product Requirements for Medical IT Products.	RE	2002	DBLP DOI BibTeX RDF
20	Wojtek Kozaczynski	Requirements, Architectures and Risks.	RE	2002	DBLP DOI BibTeX RDF
20	Sascha Konrad, Betty H. C. Cheng	Requirements Patterns for Embedded Systems.	RE	2002	DBLP DOI BibTeX RDF
20	Mariusz A. Fecko, Christopher M. Lott	Improving the Requirements Engineering Process for an Electronic Clearinghouse.	RE	2002	DBLP DOI BibTeX RDF
20	Martin S. Feather, Tim Menzies	Converging on the Optimal Attainment of Requirements.	RE	2002	DBLP DOI BibTeX RDF
20	Maya Daneva	An Assessment of the Effects of Requirements Reuse Measurements on the ERP Requirements Engineering Process.	IWSM	2000	DBLP DOI BibTeX RDF
20	Lothar Baum, Martin Becker 0002, Lars Geyer, Georg Molter	Mapping Requirements to Reusable Components Using Design Spaces.	ICRE	2000	DBLP DOI BibTeX RDF
20	Kenji Takahashi, Colin Potts, Vinay Kumar, Kenji Ota, Jeffrey D. Smith	Hypermedia Support for Collaboration in Requirements Analysis.	ICRE	1996	DBLP DOI BibTeX RDF	Inquiry Cycle, EColabor, Internet, WWW, collaboration, hypermedia
20	Klaus Pohl	PRO-ART: Enabling Requirements Pre-Traceability.	ICRE	1996	DBLP DOI BibTeX RDF
20	Philip Morris, Marcelo Masera, Marc Wilikens	Requirements Engineering and Industrial Uptake.	ICRE	1998	DBLP DOI BibTeX RDF
20	Magnus Haglind, Lars Johansson, Martin Rantzer	Experiences Integrating Requirements Engineering and Business Analysis An Empirical Study of Operations & Management System Procurement Projects.	ICRE	1998	DBLP DOI BibTeX RDF
20	Antonio Bucchiarone, Stefania Gnesi, Alessandro Fantechi, Gianluca Trentanni	An experience in using a tool for evaluating a large set of natural language requirements.	SAC	2010	DBLP DOI BibTeX RDF	natural language automated analysis, natural language processing, requirements analysis
20	Jane Cleland-Huang, Adam Czauderna, Marek Gibiec, John Emenecker	A machine learning approach for tracing regulatory codes to product specific requirements.	ICSE (1)	2010	DBLP DOI BibTeX RDF	requirements classification, traceability, regulatory compliance
20	David Blanes, Emilio Insfrán, Silvia Abrahão	Reviewing the Use of Requirements Engineering Techniques in the Development of Multi-Agent Systems.	IWANN (2)	2009	DBLP DOI BibTeX RDF	multi-agent systems, requirements engineering, systematic review
20	Birgit Bomsdorf, Daniel Sinnig	Model-Based Specification and Validation of User Interface Requirements.	HCI (1)	2009	DBLP DOI BibTeX RDF	Requirements specification use case model, task model, model simulation
20	Pietro Mazzoleni, SweeFen Goh, Richard Goodwin, Manisha Bhandar, Shyh-Kwei Chen, Juhnyoung Lee, Vibha Singhal Sinha, Senthil Mani, Debdoot Mukherjee, Biplav Srivastava, Pankaj Dhoolia, Elad Fein, Natalia Razinkov	Consultant assistant: a tool for collaborative requirements gathering and business process documentation.	OOPSLA Companion	2009	DBLP DOI BibTeX RDF	packaged applications, project management, requirements gathering, business transformation, information reuse
20	Ing Widya, Bert-Jan van Beijnum, Richard Bults, Valerie M. Jones, Hermie J. Hermens, Leif Sandsjö, Leendert Schaake, M. H. A. Huis in't Veld	Early phase requirements assessment of a teletreatment trial.	SAC	2009	DBLP DOI BibTeX RDF	goal-oriented requirements elicitation, trial design, telemedicine
20	Kristina Winbladh, Hadar Ziv, Debra J. Richardson	Eliciting required characteristics for usable requirements engineering approaches.	SAC	2009	DBLP DOI BibTeX RDF	requirements approaches, usability, survey
20	Carlos Castro-Herrera, Chuan Duan, Jane Cleland-Huang, Bamshad Mobasher	A recommender system for requirements elicitation in large-scale software projects.	SAC	2009	DBLP DOI BibTeX RDF	large-scale software engineering, requirements clustering, collaborative recommender systems
20	David Blanes, Emilio Insfrán, Silvia Abrahão	Requirements Engineering in the Development of Multi-Agent Systems: A Systematic Review.	IDEAL	2009	DBLP DOI BibTeX RDF	multi-agent systems, requirements engineering, systematic review
20	Márcia Lucena, Jaelson Castro, Carla T. L. L. Silva, Fernanda M. R. Alencar, Emanuel Santos, João Pimentel 0001	A Model Transformation Approach to Derive Architectural Models from Goal-Oriented Requirements Models.	OTM Workshops	2009	DBLP DOI BibTeX RDF	Requirements engineering, Models Transformation, Architectural design
20	Charles Pecheur, Franco Raimondi, Guillaume Brat	A formal analysis of requirements-based testing.	ISSTA	2009	DBLP DOI BibTeX RDF	requirements-based testing, coverage metrics
20	Tosca Lahiri, Mark Woodman	A Business Service Selection Model for Automated Web Service Discovery Requirements.	ICEIS	2009	DBLP DOI BibTeX RDF	Business Service Model, Web Services, Interoperability, Requirements, Discovery
20	Leonid Kof	Translation of Textual Specifications to Automata by Means of Discourse Context Modeling.	REFSQ	2009	DBLP DOI BibTeX RDF	behavior extraction, natural language processing, requirements analysis, behavior modeling
20	Li Jiang 0006, Armin Eberlein, Behrouz H. Far, Majid Mousavi	A methodology for the selection of requirements engineering techniques.	Softw. Syst. Model.	2008	DBLP DOI BibTeX RDF	Technique evaluation, Clustering, Requirements engineering, Decision support
20	Joe Zou, Christopher J. Pavlovski	Control case approach to record and model non-functional requirements.	Inf. Syst. E Bus. Manag.	2008	DBLP DOI BibTeX RDF	Control case, Use case, Non-functional requirements, NFR
20	Iain S. MacLeod	Scenario-based requirements capture for human factors integration.	Cogn. Technol. Work.	2008	DBLP DOI BibTeX RDF	HFI, Requirements, Scenarios, Cognitive, System, Trace, Functions
20	María José Escalona Cuaresma, Gustavo Aragón	NDT. A Model-Driven Approach for Web Requirements.	IEEE Trans. Software Eng.	2008	DBLP DOI BibTeX RDF	Software engineering for Internet projects, Surveys of historical development of one particular area, Requirements/Specifications
20	Mahmood Niazi, Karl Cox, June M. Verner	A measurement framework for assessing the maturity of requirements engineering process.	Softw. Qual. J.	2008	DBLP DOI BibTeX RDF	Requirements engineering, Process improvement, Process maturity
20	Jevon M. Wright, Jens Dietrich 0001	Requirements for Rich Internet Application Design Methodologies.	WISE	2008	DBLP DOI BibTeX RDF	interactive web applications, benchmark, requirements, web engineering, Rich Internet Applications
20	Pavan Kumar Chittimalli, Mary Jean Harrold	Regression test selection on system requirements.	ISEC	2008	DBLP DOI BibTeX RDF	requirements, traceability, regression testing, test case prioritization, regression test selection
20	Nan Ma, Tracy Hall, Trevor Barker	Building a Narrative Based Requirements Engineering Mediation Model.	EuroSPI	2008	DBLP DOI BibTeX RDF	Method Tailoring, Narrative Mediation, Conflict Resolution, Conflict, Requirements Negotiation
20	Rehema Baguma, Jude T. Lubega	Web Design Requirements for Improved Web Accessibility for the Blind.	ICHL	2008	DBLP DOI BibTeX RDF	E-learning, Requirements, Web Accessibility, Blind, Hybrid Learning
20	Brandon M. Malone, Ambareen Siraj	Tracking requirements and threats for secure software development.	ACM Southeast Regional Conference	2008	DBLP DOI BibTeX RDF	requirements tracking, security engineering, misuse case
20	José Luis de la Vara, Juan Sánchez	Improving Requirements Analysis through Business Process Modelling: A Participative Approach.	BIS	2008	DBLP DOI BibTeX RDF	understanding of the business, communication, business process, Requirements analysis, BPMN
20	Rolf Kluge, Thomas Hering, Roman Belter, Bogdan Franczyk	An Approach for Matching Functional Business Requirements to Standard Application Software Packages via Ontology.	COMPSAC	2008	DBLP DOI BibTeX RDF	business requirements, standard application software, ontology, requirement engineering
20	Christoph Knieke, Michaela Huhn, Malte Lochau	Modeling and Validation of Executable Requirements Using Live Activity Diagrams.	SERA	2008	DBLP DOI BibTeX RDF	Unified Modeling Language, Requirements Engineering, Model Driven Engineering, Activity Diagrams, Live Sequence Charts
20	Tamer Rafla, Pierre N. Robillard, Michel C. Desmarais	A method to elicit architecturally sensitive usability requirements: its integration into a software development process.	Softw. Qual. J.	2007	DBLP DOI BibTeX RDF	QAW, Software architecture, Software process, Usability requirements
20	Filippo Ricca, Marco Torchiano, Mariano Ceccato, Paolo Tonella	Talking tests: an empirical assessment of the role of fit acceptance tests in clarifying requirements.	IWPSE	2007	DBLP DOI BibTeX RDF	fit tables, empirical studies, requirements, acceptance testing
20	Thomas Aschauer, Gerd Dauenhauer, Patricia Derler, Wolfgang Pree, Christoph Steindl	Could an Agile Requirements Analysis Be Automated?-Lessons Learned from the Successful Overhauling of an Industrial Automation System.	Monterey Workshop	2007	DBLP DOI BibTeX RDF	use cases, requirements analysis, agile development, automation systems
20	Eriks Dobelis	Expert System for Business Decisions on Security Requirements.	OTM Workshops (1)	2007	DBLP DOI BibTeX RDF	Business Risk, Expert System, Information Security, Security Requirements
20	Matthias Heindl, Stefan Biffl	Modeling of Requirements Tracing.	CEE-SET	2007	DBLP DOI BibTeX RDF	Software Requirements Tracing, Re-Test, Tracing Activity Model, Feasibility study
20	Antti Välimäki, Jukka Kääriäinen	Requirements Management Practices as Patterns for Distributed Product Management.	PROFES	2007	DBLP DOI BibTeX RDF	Mining of patterns, Practices, Requirements management, Distributed development, Product management, Organizational patterns
20	Paolo Giorgini, Fabio Massacci, John Mylopoulos, Nicola Zannone	Requirements engineering for trust management: model, methodology, and reasoning.	Int. J. Inf. Sec.	2006	DBLP DOI BibTeX RDF	Agent-oriented software, Trust models for business and organizations, Verification and validation of software, Privilege management, Requirements Engineering, Security Engineering
20	Lena Karlsson, Martin Höst, Björn Regnell	Evaluating the practical use of different measurement scales in requirements prioritisation.	ISESE	2006	DBLP DOI BibTeX RDF	costvalue approach, ordinal scale data, ratio scale data, requirements prioritisation
20	Prasanna Padmanabhan, Robyn R. Lutz	Tool-Supported Verification of Product Line Requirements.	Autom. Softw. Eng.	2005	DBLP DOI BibTeX RDF	requirements verification, feature-interaction resolution, variability, product line, consistency checking, product family, dependency constraints
20	John Viega	Building security requirements with CLASP.	ACM SIGSOFT Softw. Eng. Notes	2005	DBLP DOI BibTeX RDF	security requirements, application security, security process
20	Andreas Gregoriades, Alistair G. Sutcliffe	Scenario-Based Assessment of Nonfunctional Requirements.	IEEE Trans. Software Eng.	2005	DBLP DOI BibTeX RDF	Nonfunctional requirements validation, scenario-based testing, systems engineering, Bayesian belief networks
20	Deepak S. Yavagal, Seok Won Lee, Gail-Joon Ahn, Robin A. Gandhi	Common criteria requirements modeling and its uses for quality of information assurance (QoIA).	ACM Southeast Regional Conference (2)	2005	DBLP DOI BibTeX RDF	information assurance metrics & measures, ontology, requirements modeling, common criteria
20	Jemima Rossmorris, Susan Stepney	Requirements as Conjectures: Intuitive DVD Menu Navigation.	ZB	2005	DBLP DOI BibTeX RDF	requirements, Z, DVD, conjectures
20	Emmanuel Letier, Jeff Kramer, Jeff Magee, Sebastián Uchitel	Monitoring and control in scenario-based requirements analysis.	ICSE	2005	DBLP DOI BibTeX RDF	implied scenarios, scenario-based requirements elaboration, message sequence charts
20	Rubén Fuentes, Jorge J. Gómez-Sanz, Juan Pavón	Requirements Elicitation for Agent-Based Applications.	AOSE	2005	DBLP DOI BibTeX RDF	Multi-Agent Systems Development, Activity Checklist, Requirements Elicitation, Activity Theory
20	Talha Javed, Manzil e Maqsood, Qaiser S. Durrani	A study to investigate the impact of requirements instability on software defects.	ACM SIGSOFT Softw. Eng. Notes	2004	DBLP DOI BibTeX RDF	change request (CR's)1, high/medium/low change requests, pre/post release changes, severity-1/severity-2 defects, defects, requirements change
20	Neil A. M. Maiden, Alexis Gizikis, Suzanne Robertson	Provoking Creativity: Imagine What Your Requirements Could Be Like.	IEEE Softw.	2004	DBLP DOI BibTeX RDF	creativity workshops, requirements engineering
20	K. Suzanne Barber, Thomas J. Graser, Jim Holt, Geoff Baker	Arcade: early dynamic property evaluation of requirements using partitioned software architecture models.	Requir. Eng.	2003	DBLP DOI BibTeX RDF	Software architecture, Requirements models, Dynamic properties
20	Darrell Raymond	Authorisation Requirements on a Budget.	Requir. Eng.	2002	DBLP DOI BibTeX RDF	Authorization, Dependency analysis, Security requirements
20	Evangelia Kavakli	Goal-Oriented Requirements Engineering: A Unifying Framework.	Requir. Eng.	2002	DBLP DOI BibTeX RDF	Goal analysis, Goal modelling, Goal-oriented requirements engineering, Method integration
20	Peter Sawyer, Paul Rayson, Roger Garside	REVERE: Support for Requirements Synthesis from Documents.	Inf. Syst. Frontiers	2002	DBLP DOI BibTeX RDF	document archaeology, natural language processing, requirements engineering, systems engineering
20	Carina Frota Alves, Anthony Finkelstein	Challenges in COTS decision-making: a goal-driven requirements engineering perspective.	SEKE	2002	DBLP DOI BibTeX RDF	decision-making COTS-based system, requirements engineering
20	Stanislaw Szejko	Requirements Driven Quality Control.	COMPSAC	2002	DBLP DOI BibTeX RDF	quality tree model, QFD method, GQM approach, requirements specification, quality control
20	Rosío Alvarez	Discourse Analysis of Requirements and Knowledge Elicitation Interviews.	HICSS	2002	DBLP DOI BibTeX RDF	requirements analysis, narratives, interviews, discourse analysis, knowledge elicitation
20	Didar Zowghi, Vincenzo Gervasi, Andrew McRae	Using Default Reasoning to Discover Inconsistencies in Natural Language Requirements.	APSEC	2001	DBLP DOI BibTeX RDF	s cenarios, Requirements, natural language, inconsistency, default logic
20	Robert D. Galliers, Jacky Swan	There's More to Information Systems Development than Structured Approaches: Information Requirements Analysis as a Socially Mediated Process.	Requir. Eng.	2000	DBLP DOI BibTeX RDF	Case study research, Cognitive schemas, Formal and informal information, Information requirements analysis, Management of knowledge, Information systems development, Structured approaches
20	David C. Sutton	Linguistic Problems with Requirements and Knowledge Elicitation.	Requir. Eng.	2000	DBLP DOI BibTeX RDF	Prototyping, Requirements, Representation, Linguistic, Epistemology, Elicitation
20	Ben L. Di Vito	High-automation proofs for properties of requirements models.	Int. J. Softw. Tools Technol. Transf.	2000	DBLP DOI BibTeX RDF	Avionics software, Proof strategies, Formal methods, Theorem proving, Requirements analysis
20	Jo Orr, Liisa von Hellens	Skill requirements of IT&T professionals and graduates: an Australian study research-in-progress.	SIGCPR	2000	DBLP DOI BibTeX RDF	IT&T skill requirements, Australia
20	Nikos Prekas, Pericles Loucopoulos	Combining Strategy and Deliberation in the Requirements Engineering Process.	DEXA Workshops	2000	DBLP DOI BibTeX RDF	prescriptive stance, descriptive stance, requirements engineering, process modelling, systems analysis, reasoning, systems development
20	Suzanne Robertson, James Robertson	Reliable Requirements through the Quality Gateway.	DEXA Workshops	1999	DBLP DOI BibTeX RDF	Testing, Requirements
20	Filippo Lanubile, Forrest Shull, Victor R. Basili	Experimenting with Error Abstraction in Requirements Documents.	IEEE METRICS	1998	DBLP DOI BibTeX RDF	error abstraction, software requirements, Defect detection, perspective-based reading
20	Peter Hruschka	Detailing and deriving system requirements.	ECBS	1997	DBLP DOI BibTeX RDF	system development methods, systems analysis, system requirements, software engineering methods
20	Bénédicte Dano, Henri Briand, Franck Barbier	Progressing Towards Object-Oriented Requirements Specifications by using the USE CASE Concept.	ECBS	1996	DBLP DOI BibTeX RDF	dynamic specifications, verification, requirements engineering, formalization, object-oriented analysis
20	Robert Darimont, Axel van Lamsweerde	Formal Refinement Patterns for Goal-Driven Requirements Elaboration.	SIGSOFT FSE	1996	DBLP DOI BibTeX RDF	goal-drive requirements engineering, reuse of specifications and proof, formal methods, design patterns, refinement
20	Aphrodite Tsalgatidou, Vassileios Karakostas, Pericles Loucopoulos	Rule-Based Requirements Specification and Validation.	CAiSE	1990	DBLP DOI BibTeX RDF	Petri-nets, animation, logic programming, conceptual modelling, requirements specification, rule bases, executable specifications
19	Ing Widya, Richard Bults, Bert-Jan van Beijnum, Leif Sandsjö, Leendert Schaake, Rianne Huis in't Veld, Val Jones 0001, Hermie J. Hermens	Requirements Elicitation in a Telemedicine Pain-treatment Trial.	RE	2009	DBLP DOI BibTeX RDF	trial design, telemedicine, requirements elicitation, goal-oriented
19	Philipp Liegl, Rainer Schuster, Marco Zapletal, Christian Huemer, Hannes Werthner, Michael Aigner, Martin Bernauer, Bjoern Klinger, Michaela Mayr, Ramin Mizani, Martin Windisch	[vem: xi: ] - A Methodology for Process Based Requirements Engineering.	RE	2009	DBLP DOI BibTeX RDF	process based requirements engineering, business process modeling notation, service oriented architectures
19	Jens H. Weber-Jahnke, Adeniyi Onabajo	Finding Defects in Natural Language Confidentiality Requirements.	RE	2009	DBLP DOI BibTeX RDF	goal-based models, annotations, requirements analysis, conflicts, exceptions, incompleteness, defaults
19	Juan Pablo Carvallo 0001, Xavier Franch	On the Use of Requirements for Driving Call-for-Tender Processes for Procuring Coarse-grained OTS Components.	RE	2009	DBLP DOI BibTeX RDF	OTS componentes, call-for-tender processes, requirements engineering
19	Orlena Gotel, Patrick Mäder	How to Select a Requirements Management Tool: Initial Steps.	RE	2009	DBLP DOI BibTeX RDF	Expectation management, tool selection, requirements engineering, tool evaluation
19	Jeremy C. Maxwell, Annie I. Antón	Developing Production Rule Models to Aid in Acquiring Requirements from Legal Texts.	RE	2009	DBLP DOI BibTeX RDF	production rule modeling, logic programming, Requirements engineering, regulatory compliance
19	Hendrik Post, Carsten Sinz, Florian Merz 0001, Thomas Gorges, Thomas Kropf	Linking Functional Requirements and Software Verification.	RE	2009	DBLP DOI BibTeX RDF	verification, bounded model checking, functional requirements
19	Carlos Castro-Herrera, Jane Cleland-Huang, Bamshad Mobasher	Enhancing Stakeholder Profiles to Improve Recommendations in Online Requirements Elicitation.	RE	2009	DBLP DOI BibTeX RDF	Recommender Systems, Requirements, Elicitation
19	Carlo Ghezzi, Giordano Tamburrelli	Reasoning on Non-Functional Requirements for Integrated Services.	RE	2009	DBLP DOI BibTeX RDF	Non-Functional Requirements, Integrated Services, Discrete Time Markov Chains