A wide variety of media can be used in learning, including distance learning, such as print, lectures, conference sections, tutors, pictures, video, sound, and computers. Any one instance of distance learning will make choices among these media, perhaps using several.

Multimedia in Learning

ing WS1S Systems to Verify Parameterized Networks . . . . . . . . . . . . 188 Kai Baukus, Saddek Bensalem, Yassine Lakhnech and Karsten Stahl FMona: A Tool for Expressing Validation Techniques over Infinite State Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 J.-P. Bodeveix and M. Filali Transitive Closures of Regular Relations for Verifying Infinite-State Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Bengt Jonsson and Marcus Nilsson Diagnostic and Test Generation Using Static Analysis to Improve Automatic Test Generation . . . . . . . . . . . . . 235 Marius Bozga, Jean-Claude Fernandez and Lucian Ghirvu Efficient Diagnostic Generation for Boolean Equation Systems . . . . . . . . . . . . 251 Radu Mateescu Efficient Model-Checking Compositional State Space Generation with Partial Order Reductions for Asynchronous Communicating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266 Jean-Pierre Krimm and Laurent Mounier Checking for CFFD-Preorder with Tester Processes . . . . . . . . . . . . . . . . . . . . . . . 283 Juhana Helovuo and Antti Valmari Fair Bisimulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 Thomas A. Henzinger and Sriram K. Rajamani Integrating Low Level Symmetries into Reachability Analysis . . . . . . . . . . . . . 315 Karsten Schmidt Model-Checking Tools Model Checking Support for the ASM High-Level Language . . . . . . . . . . . . . . 331 Giuseppe Del Castillo and Kirsten Winter Table of

Tools and Algorithms for the Construction and Analysis of Systems. Proc. TACAS 2009

Blockchain is a decentralized transaction and data management technology developed first for Bitcoin cryptocurrency. The interest in Blockchain technology has been increasing since the idea was coined in 2008. The reason for the interest in Blockchain is its central attributes that provide security, anonymity and data integrity without any third party organization in control of the transactions, and therefore it creates interesting research areas, especially from the perspective of technical challenges and limitations. In this research, we have conducted a systematic mapping study with the goal of collecting all relevant research on Blockchain technology. Our objective is to understand the current research topics, challenges and future directions regarding Blockchain technology from the technical perspective. We have extracted 41 primary papers from scientific databases. The results show that focus in over 80% of the papers is on Bitcoin system and less than 20% deals with other Blockchain applications including e.g. smart contracts and licensing. The majority of research is focusing on revealing and improving limitations of Blockchain from privacy and security perspectives, but many of the proposed solutions lack concrete evaluation on their effectiveness. Many other Blockchain scalability related challenges including throughput and latency have been left unstudied. On the basis of this study, recommendations on future research directions are provided for researchers.

/pdf/where-is-current-research-on-blockchain-technology-a-530we6hlvi.pdf

Where Is Current Research on Blockchain Technology?-A Systematic Review.

The Object Management Group's (OMG) Model Driven Architecture (MDA) strategy envisages a world where models play a more direct role in software production, being amenable to manipulation and transformation by machine. Model Driven Engineering (MDE) is wider in scope than MDA. MDE combines process and analysis with architecture. This article sets out a framework for model driven engineering, which can be used as a point of reference for activity in this area. It proposes an organisation of the modelling 'space' and how to locate models in that space. It discusses different kinds of mappings between models. It explains why process and architecture are tightly connected. It discusses the importance and nature of tools. It identifies the need for defining families of languages and transformations, and for developing techniques for generating/configuring tools from such definitions. It concludes with a call to align metamodelling with formal language engineering techniques.

Model Driven Engineering

Besides attracting a billion dollar economy, Bitcoin revolutionized the field of digital currencies and influenced many adjacent areas. This also induced significant scientific interest. In this survey, we unroll and structure the manyfold results and research directions. We start by introducing the Bitcoin protocol and its building blocks. From there we continue to explore the design space by discussing existing contributions and results. In the process, we deduce the fundamental structures and insights at the core of the Bitcoin protocol and its applications. As we show and discuss, many key ideas are likewise applicable in various other fields, so that their impact reaches far beyond Bitcoin itself.

Bitcoin and Beyond: A Technical Survey on Decentralized Digital Currencies

We provide a first systematic account of opportunities and limitations of anti-money laundering (AML) in Bitcoin, a decentralized cryptographic currency proliferating on the Internet. Our starting point is the observation that Bitcoin attracts criminal activity as many say it is an anonymous transaction system. While this claim does not stand up to scrutiny, several services offering increased transaction anonymization have emerged in the Bitcoin ecosystem - such as Bitcoin Fog, BitLaundry, and the Send Shared functionality of Blockchain.info. Some of these services routinely handle the equivalent of 6-digit dollar amounts. In a series of experiments, we use reverse-engineering methods to understand the mode of operation and try to trace anonymized transactions back to our probe accounts. While Bitcoin Fog and Blockchain.info successfully anonymize our test transactions, we can link the input and output transactions of BitLaundry. Against the backdrop of these findings, it appears unlikely that a Know-Your-Customer principle can be enforced in the Bitcoin system. Hence, we sketch alternative AML strategies accounting for imperfect knowledge of true identities but exploiting public information in the transaction graph, and discuss the implications for Bitcoin as a decentralized currency.

/pdf/an-inquiry-into-money-laundering-tools-in-the-bitcoin-1bhkrcg20a.pdf

An inquiry into money laundering tools in the Bitcoin ecosystem

Predictive modeling approaches in business process management provide a way to streamline operational business processes. For instance, they can warn decision makers about undesirable events that are likely to happen in the future, giving the decision maker an opportunity to intervene. The topic is gaining momentum in process mining, a field of research that has traditionally developed tools to discover business process models from data sets of past process behavior. Predictive modeling techniques are built on top of process-discovery algorithms. As these algorithms describe business process behavior using models of formal languages (e.g., Petri nets), strong language biases are necessary in order to generate models with the limited amounts of data included in the data set. Naturally, corresponding predictive modeling techniques reflect these biases. Based on theory from grammatical inference, a field of research that is concerned with inducing language models, we design a new predictive modeling technique based on weaker biases. Fitting a probabilistic model to a data set of past behavior makes it possible to predict how currently running process instances will behave in the future. To clarify how this technique works and to facilitate its adoption, we also design a way to visualize the probabilistic models. We assess the effectiveness of the technique in an experimental evaluation with synthetic and real-world data.

/pdf/comprehensible-predictive-models-for-business-processes-2sqrpf3mmq.pdf

Comprehensible predictive models for business processes

If Bitcoin becomes the prevalent payment system on the Internet, crime fighters will join forces with regulators and enforce blacklisting of transaction prefixes at the parties who offer real products and services in exchange for bitcoin. Blacklisted bitcoins will be hard to spend and therefore less liquid and less valuable. This requires every recipient of Bitcoin payments not only to check all incoming transactions for possible blacklistings, but also to assess the risk of a transaction being blacklisted in the future. We elaborate this scenario, specify a risk model, devise a prediction approach using public knowledge, and present preliminary results using data from selected known thefts. We discuss the implications on markets where bitcoins are traded and critically revisit Bitcoin’s ability to serve as a unit of account.

http://fc14.ifca.ai/bitcoin/papers/bitcoin14_submission_15.pdf

Towards Risk Scoring of Bitcoin Transactions

Proof-of-Work (PoW), a well-known principle to ration resource access in client-server relations, is about to experience a renaissance as a mechanism to protect the integrity of a global state in distributed transaction systems under decentralized control. Most prominently, the Bitcoin cryptographic currency protocol leverages PoW to 1) prevent double spending and 2) establish scarcity, two essential properties of any electronic currency. This paper asks the important question whether this approach is generally viable. Citing actual data, it provides a first cut of an answer by estimating the resource requirements, in terms of operating cost and ecological footprint, of a suitably dimensioned PoW infrastructure and comparing them to three attack scenarios. The analysis is inspired by Bitcoin, but generalizes to potential successors, which fix Bitcoin’s technical and economic teething troubles discussed in the literature.

https://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID2041492_code1829477.pdf?abstractid=2041492&mirid=5&type=2

Can We Afford Integrity by Proof-of-Work? Scenarios Inspired by the Bitcoin Currency

Proof-of-Work (PoW), a well-known principle to ration resource access in client-server relations, is about to experience a renaissance as a mechanism to protect the integrity of a global state in distributed transaction systems under decentralized control. Most prominently, the Bitcoin cryptographic currency protocol leverages PoW to (1) prevent double spending and (2) establish scarcity, two essential properties of any electronic currency. This chapter asks the important question whether this approach is generally viable. Citing actual data, it provides a first cut of an answer by estimating the resource requirements, in terms of operating cost and ecological footprint, of a suitably dimensioned PoW infrastructure and comparing them to three attack scenarios. The analysis is inspired by Bitcoin, but generalizes to potential successors, which fix Bitcoin’s technical and economic teething troubles discussed in the literature.

/pdf/can-we-afford-integrity-by-proof-of-work-scenarios-inspired-1tlkg207jf.pdf

Dominic Breuker

Papers

An inquiry into money laundering tools in the Bitcoin ecosystem

Comprehensible predictive models for business processes

Towards Risk Scoring of Bitcoin Transactions

Can We Afford Integrity by Proof-of-Work? Scenarios Inspired by the Bitcoin Currency

Can We Afford Integrity by Proof-of-Work? Scenarios Inspired by the Bitcoin Currency