Normal accidents. Living with high-risk technologies

The History of Economic Analysis

WITH the ever-widening scope of modern mathematical analysis and its many ramifications, it is quite impossible to include, in a single volume of reasonable size, an adequate and exhaustive discussion of the calculus in its more advanced stages. It therefore becomes necessary, in planning a thoroughly sound course in the subject, to consider several important aspects of the vast field confronting a modern writer. The limitation of space renders the selection of subject-matter fundamentally dependent upon the aim of the course, which may or may not be related to the content of specific examination syllabuses. Logical development, too, may lead to the inclusion of many topics which, at present, may only be of academic interest, while others, of greater practical value, may have to be omitted. The experience and training of the writer may also have, more or less, a bearing on both these considerations.Advanced CalculusBy Dr. C. A. Stewart. Pp. xviii + 523. (London: Methuen and Co., Ltd., 1940.) 25s.

Advanced Calculus I

Software fault localization, the act of identifying the locations of faults in a program, is widely recognized to be one of the most tedious, time consuming, and expensive – yet equally critical – activities in program debugging. Due to the increasing scale and complexity of software today, manually locating faults when failures occur is rapidly becoming infeasible, and consequently, there is a strong demand for techniques that can guide software developers to the locations of faults in a program with minimal human intervention. This demand in turn has fueled the proposal and development of a broad spectrum of fault localization techniques, each of which aims to streamline the fault localization process and make it more effective by attacking the problem in a unique way. In this article, we catalog and provide a comprehensive overview of such techniques and discuss key issues and concerns that are pertinent to software fault localization as a whole.

A Survey on Software Fault Localization

Experimental Economics became an autonomous field of research after WWII in concomitance with the increasing interest in Microeconomic theory. The VonNeumann-Morgenstern’s Expected Utility Theory gave a lot of opportunity to test behaviour trough lotteries (Allais Paradox...). In 1952 the Conference of Santa Monica grounded Experimental Economics on more theoretical basis and gave to the discipline an autonomous methodological structure.

实验经济学（Experimental Economics）研究思路及成果应用简述

The invention relates to the fields of tokenisation, blockchain and smart contract technologies. It provides a technical arrangement which simplifies the automated management of contracts. The invention comprises a method and system which use a computer-based repository for storage of the contract. The contract is then represented by a transaction on the blockchain. Metadata within the transaction's script includes a hash of the contract and a means of identifying its location within the repository. The transaction also includes an unspent output (UTXO) which indicates its status as an open (ie not terminated) contract. The contract is terminated by spending the output at a later point in time, for example, using n Lock Time + Check Lock Time Verify (CLTV). By combining this concept with other techniques and computing components, the invention can provide a powerful mechanism for implementing various tasks such as renewing or rolling over the contract, or dividing it into sub-contracts or conditions. Furthermore, as the status and existence of the contract is evidence via the blockchain, this provides a permanent, publicly visible and non-alterable record of the contract.

Registry and automated management method for blockchain-enforced smart contracts

Often we hear controversial opinions in digital forensics on the required or desired number of passes to utilize for properly overwriting, sometimes referred to as wiping or erasing, a modern hard drive. The controversy has caused much misconception, with persons commonly quoting that data can be recovered if it has only been overwritten once or twice. Moreover, referencing that it actually takes up to ten, and even as many as 35 (referred to as the Gutmann scheme because of the 1996 Secure Deletion of Data from Magnetic and Solid-State Memory published paper by Peter Gutmann) passes to securely overwrite the previous data. One of the chief controversies is that if a head positioning system is not exact enough, new data written to a drive may not be written back to the precise location of the original data. We demonstrate that the controversy surrounding this topic is unfounded.

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Overwriting Hard Drive Data: The Great Wiping Controversy

Bitcoins and Blockchain technologies are attracting the attention of different scientific communities. In addition, their widespread industrial applications and the continuous introduction of cryptocurrencies are also stimulating the attention of the public opinion. The underlying structure of these technologies constitutes one of their core concepts. In particular, they are based on peer-to-peer networks. Accordingly, all nodes lie at the same level, so that there is no place for privileged actors as, for instance, banking institutions in classical financial networks. In this work, we perform a preliminary investigation on two kinds of network, i.e. the Bitcoin network and the Bitcoin Cash network. Notably, we analyze their global structure and we try to evaluate if they are provided with a small-world behavior. Results suggest that the principle known as 'fittest-gets-richer', combined with a continuous increasing of connections, might constitute the mechanism leading these networks to reach their current structure. Moreover, further observations open the way to new investigations into this direction.

From Bitcoin to Bitcoin Cash: a network analysis

The invention provides a computer- implemented solution for controlling access to a computer-related resource such as, for example, a digital wallet. In one or more embodiments, the wallet may be implemented using a blockchain such as the Bitcoin blockchain but the invention is not limited in this regard. Use of the invention during the initial set-up of the wallet can enable subsequent operations such as wallet transactions to be handled in a secure manner over an insecure channel such as the internet. A method according to an embodiment of the invention can comprise the steps of splitting a verification element (such as a private key in an asymmetric cryptography pair) into a plurality of shares; determining a common secret at two or more nodes in a network; and using the common secret to transmit at least one share of the verification element between the two or more nodes. The shares can be split such that no share on its own is sufficient to arrive at the verification element. This means that no one party stores the entire private key, providing for enhanced security of the key. Two or more shares are required to restore the key. The shares are stored at separate locations one of which is an independent back-up or safe-storage location. If one of the other shares becomes unavailable, the share can be retrieved from back up to ensure that the key (and thus the controlled resource) is still accessible. To ensure safe transmission of the share(s), the common secret is generated at two different nodes independently of each other and then used to generate an encryption key. The encryption key can be used to encrypt at least one share of the verification element, or a message comprising it, to ensure that the share(s) are transmitted securely.

Secure multiparty loss resistant storage and transfer of cryptographic keys for blockchain based systems in conjunction with a wallet management system

The invention comprise s a computer - implemented method and system for control ling an exchange process, such as a loan, conducted between at least two parties via a blockchain such as the Bitcoi n blockchain. A method according to the invention may comprise the step of generating a first blockchain transaction which includes a redeem script. The redeem script comprises a cryptographic public key associated with an initiating party and metadata w hich includes a hash of an exchange - related document; a redeem address; and an amount of digital currency. A second blockchain transaction is generated and published to the blockchain so as to spend the digital currency to the redeem address. This provid es the advantage that the further transaction will be publically available and thus detectable by other parties once it has been published. The further transaction can provide the information necessary to trigger a response e.g. an offer from another (res ponding) party who publishes their response on the blockchain. Thus, the exchange process can be implemented via a multi - transaction mechanism on the blockchain rather than an alternative medium. The exchange related document may be an invitation (offer/ request) which is stored off - block in a repository such as a Distributed Hash Table (DHT). The invitation may be an invitation to engage in a contract. A smart contract (and associated blockchain transaction) may be formed upon condition that a plurality of participants (e.g. lenders/borrowers) are matched with each other via one or more responses effected via transactions on the blockchain.

Craig Steven Wright

Papers

Registry and automated management method for blockchain-enforced smart contracts

Overwriting Hard Drive Data: The Great Wiping Controversy

From Bitcoin to Bitcoin Cash: a network analysis

Secure multiparty loss resistant storage and transfer of cryptographic keys for blockchain based systems in conjunction with a wallet management system

A method for secure peer-to-peer communication on a blockchain