Renegotiation and recursion in Bitcoin contracts

BitML is a process calculus to express smart contracts that can be run on Bitcoin. One of its current limitations is that, once a contract has been stipulated, the participants cannot renegotiate its terms: this prevents expressing common financial contracts, where funds have to be added by participants at run-time. In this paper, we extend BitML with a new primitive for contract renegotiation. At the same time, the new primitive can be used to write recursive contracts, which was not possible in the original BitML. We show that, despite the increased expressiveness, it is still possible to execute BitML on standard Bitcoin, preserving the security guarantees of BitML.Comment: Full version of the paper presented at COORDINATION 202

Verifying liquidity of recursive Bitcoin contracts

Smart contracts - computer protocols that regulate the exchange of crypto-assets in trustless environments - have become popular with the spread of blockchain technologies. A landmark security property of smart contracts is liquidity: in a non-liquid contract, it may happen that some assets remain frozen, i.e. not redeemable by anyone. The relevance of this issue is witnessed by recent liquidity attacks to Ethereum, which have frozen hundreds of USD millions. We address the problem of verifying liquidity on BitML, a DSL for smart contracts with a secure compiler to Bitcoin, featuring primitives for currency transfers, contract renegotiation and consensual recursion. Our main result is a verification technique for liquidity. We first transform the infinite-state semantics of BitML into a finite-state one, which focusses on the behaviour of a chosen set of contracts, abstracting from the moves of the context. With respect to the chosen contracts, this abstraction is sound, i.e. if the abstracted contract is liquid, then also the concrete one is such. We then verify liquidity by model-checking the finite-state abstraction. We implement a toolchain that automatically verifies liquidity of BitML contracts and compiles them to Bitcoin, and we assess it through a benchmark of representative contracts.Comment: arXiv admin note: text overlap with arXiv:2003.0029

Formal Methods for Secure Bitcoin Smart Contracts

The notion of smart contracts was introduced in 1997 by Nick Szabo, to describe agreements among mutually distrusting parties that can be automatically enforced without resorting to a trusted intermediary. Then, the idea was mostly forgotten due to the technical impossibility to implement it. The advent of distributed ledger technologies, pioneered by Bitcoin, provided a technical foundation to reshape and develop smart contracts. Since smart contracts handle the ownership of valuable assets, attackers may be tempted to exploit vulnerabilities in their implementation to steal or tamper with these assets. For instance, a series of vulnerabilities in Ethereum contracts have been exploited, causing money losses in the order of hundreds of millions of dollars. Over the last years, a variety of smart contracts for Bitcoin have been proposed, both by the academic community and by that of developers. However, the heterogeneity in their treatment, the informal (often incomplete or imprecise) descriptions, and the use of poorly documented Bitcoin features, poses obstacles to the development of secure smart contracts. Using formal models and domain-specific languages to describe the behaviour of the underlying platform, and to model contracts, could help to overcome these security issues, by reducing the distance between the intended behaviour of a contract and the implementation. In this thesis, we propose a formal model of Bitcoin transactions, which is the foundation for a new process algebra for defining Bitcoin smart contracts. Furthermore, we present a toolchain for developing smart contracts in BitML, a domain-specific language based on the contributions of this thesis. Moreover, we propose a new extension to Bitcoin, called neighbourhood covenants, which extends its expressiveness as a smart contract platform. We then exploit neighbourhood covenants to implement fungible tokens on Bitcoin

Parafiction as Matter and Method

The thesis examines the different ways in which artists have engaged with parafiction in the twentieth and twenty-first century. Parafiction – a fiction experienced as fact - has become an important mode of practice within contemporary art, with this shift concurrent to the exponential growth of digital technology. The term contemporary art is applied here in an expanded sense to acknowledge the effect of digital processes and matter on art and to include practices that use technology as form or subject or a combination of the two. Parafiction appears in various materialities, both digital and physical, and could be described as having neomateriality. Parafiction as Matter and Method inevitably locates the research within the context of the digital. The research investigates how the usage of parafiction has changed since 1989 with the rapid advancement of technology and widespread access to the internet. Changes in the social and political landscape have also affected the function of parafiction in contemporary society. These conditions are not necessarily time bound or linear. Drawing upon and extending Carrie Lambert-Beatty’s concept of parafictions (2009), the research is rooted in art history and contemporary art for its theoretical frameworks. The research engages deeply with art history and contemporary art in an expanded sense to contextualise and analyse parafictions, whilst utilising an interdisciplinary approach. To augment this deep context the research has combined the following fields: artistic practice, digital cultures, media studies, performance art, philosophy and politics. By synthesising this broad range of fields the research is original and complex in its approach aiming to consider the topic at a planetary scale within the bounds of the possible. As an overarching method, this research applies fiction as a method to produce new knowledge. The research uses primary and secondary methods including the production of a body of artwork and diagrammatic reasoning to augment the theoretical proposal. The art practice is employed as a method to synthesise the theory with practice and to apply the knowledge learnt outside of its text-based constraints. The practice appears as interludes interspersed throughout the thesis, that produce a duo-linear narrative with the aim of the thesis becoming an artwork in its own right. Primary data collection included interviews with relevant artists, attending and speaking at international conferences and research visits to exhibitions. This thesis has evolved through the attendance at international conferences as speaker and audience member, peer-reviewed publication, interaction with academic peers and research visits to exhibitions. This thesis evaluates how parafiction renegotiates physical and digital spatio-temporal parameters to offer alternatives for the present, pasts and futures, for both human and nonhuman users of those spaces. As parafiction becomes matter it has the ability to converge the digital and the physical to extend the lives of artworks beyond their initial existence. It is argued that fictioning methods have the most impact within contemporary art in its most expanded sense. The research advocates for parafiction as a vital method, found within artistic practice in the twentieth and twenty-first century, which produces new information and perspectives. This thesis uniquely concludes that parafiction is matter, as material that intersects and interacts with the modularity of digital technologies. Significantly, the research has found that parafiction acts as an additional module that connects physical and digital spatio-temporal with alternative potential for pasts, presents, and futures

Investment in capital markets

Investment in Capital Markets creates a strategic vision on the financial capital investment in the capital markets with the aim to get an increased return premium in the short and long time periods. The book is written with a main goal to explain the pros and cons of the financial capital investment in the capital markets, discussing the sophisticated investment concepts and techniques in the simple understandable readable general format language. We would like to highlight the three interesting facts about the book: 1. It is centered on the consideration of the modern investment products, the investment vehicles and the investment mediums for the financial capital investment in the capital markets; 2. It is focused on the financial risk calculation and mitigation techniques for the financial capital investment in the financial capital markets. 3. It is aimed to describe the quantum winning virtuous investment strategies creation and execution techniques during the financial capital investment in the capital markets. The investors, financiers, economists, financial analysts, financial traders, financial advisers, lawmakers, policy analysts, subject experts, professors, and students will certainly enjoy a breathtaking splendid learning journey with the explained new ideas, established concepts and outlined future prospects toward the financial capital investment in the capital markets with the aim to get an increased return premium in the short and long time periods

Fuelling the zero-emissions road freight of the future: routing of mobile fuellers

The future of zero-emissions road freight is closely tied to the sufficient availability of new and clean fuel options such as electricity and Hydrogen. In goods distribution using Electric Commercial Vehicles (ECVs) and Hydrogen Fuel Cell Vehicles (HFCVs) a major challenge in the transition period would pertain to their limited autonomy and scarce and unevenly distributed refuelling stations. One viable solution to facilitate and speed up the adoption of ECVs/HFCVs by logistics, however, is to get the fuel to the point where it is needed (instead of diverting the route of delivery vehicles to refuelling stations) using "Mobile Fuellers (MFs)". These are mobile battery swapping/recharging vans or mobile Hydrogen fuellers that can travel to a running ECV/HFCV to provide the fuel they require to complete their delivery routes at a rendezvous time and space. In this presentation, new vehicle routing models will be presented for a third party company that provides MF services. In the proposed problem variant, the MF provider company receives routing plans of multiple customer companies and has to design routes for a fleet of capacitated MFs that have to synchronise their routes with the running vehicles to deliver the required amount of fuel on-the-fly. This presentation will discuss and compare several mathematical models based on different business models and collaborative logistics scenarios

Business Cycles in Economics

The business cycles are generated by the oscillating macro-/micro-/nano- economic output variables in the economy of the scale and the scope in the amplitude/frequency/phase/time domains in the economics. The accurate forward looking assumptions on the business cycles oscillation dynamics can optimize the financial capital investing and/or borrowing by the economic agents in the capital markets. The book's main objective is to study the business cycles in the economy of the scale and the scope, formulating the Ledenyov unified business cycles theory in the Ledenyov classic and quantum econodynamics