Catching Cheats: Detecting Strategic Manipulation in Distributed Optimisation of Electric Vehicle Aggregators

Given the rapid rise of electric vehicles (EVs) worldwide, and the ambitious targets set for the near future, the management of large EV fleets must be seen as a priority. Specifically, we study a scenario where EV charging is managed through self-interested EV aggregators who compete in the day-ahead market in order to purchase the electricity needed to meet their clients' requirements. With the aim of reducing electricity costs and lowering the impact on electricity markets, a centralised bidding coordination framework has been proposed in the literature employing a coordinator. In order to improve privacy and limit the need for the coordinator, we propose a reformulation of the coordination framework as a decentralised algorithm, employing the Alternating Direction Method of Multipliers (ADMM). However, given the self-interested nature of the aggregators, they can deviate from the algorithm in order to reduce their energy costs. Hence, we study the strategic manipulation of the ADMM algorithm and, in doing so, describe and analyse different possible attack vectors and propose a mathematical framework to quantify and detect manipulation. Importantly, this detection framework is not limited the considered EV scenario and can be applied to general ADMM algorithms. Finally, we test the proposed decentralised coordination and manipulation detection algorithms in realistic scenarios using real market and driver data from Spain. Our empirical results show that the decentralised algorithm's convergence to the optimal solution can be effectively disrupted by manipulative attacks achieving convergence to a different non-optimal solution which benefits the attacker. With respect to the detection algorithm, results indicate that it achieves very high accuracies and significantly outperforms a naive benchmark

Private information, bid-ask spreads and return volatility in the foreign exchange market

Trading volume and order flow have both been closely associated with informedtrader activity in the market microstructure literature. Using theory that explainsregular intraday patterns in trading data, we transform these variables into proxies forprivate information and examine their relationships with bid-ask spreads and returnvolatility. We use a unique and unusually rich high-frequency intraday dataset fromthe world’s largest financial market, namely, the electronic inter-dealer spot foreignexchange market. Our analysis takes account of institutional features peculiar to thisorder-driven market. Our empirical results strongly affirm our theoreticalunderstanding of how these markets work. They also reveal how the structure of theinter-dealer spot FX market affects exchange rate volatility

The Brexit vote and currency markets

This paper studies the effect of the Brexit vote on the intraday correlation and volatility transmission among major currencies. We find that the vote causes an increase in the correlation among the safe-haven currencies of the Swiss franc and Japanese yen as well as gold, and also find a decrease in their correlation with the directly involved currencies of British sterling and the Euro. These changes are due to the appreciation of the former group and the depreciation of the latter group which represents a flight to quality of investors. We also observe a substantial decrease in volatility transmission between British sterling and the Euro following the Brexit vote due to lower levels of market integration. However the volatility transmission among the currencies has increased in general and their net spillover is positively correlated with their level of volatility and trading activities. Therefore we document the significant impact of the politically important Brexit vote on the high frequency correlation and volatility spillover in the foreign exchange market

Alexandrine Schniewind: L'Ethique du Sage chez Plotin. Le paradigme du spoudaios.

The focus of this monograph is, as its title suggests, the ethical stance of the spoudaios in Plotinus' Enneads. Schniewind, hereafter S, provides in her introduction an accurate summary of the work of previous writers on Plotinus' ethical theory. This summary demonstrates that there is some disagreement as to whether or not Plotinus provides an ethic that is applicable to the ordinary man, as opposed to the spoudaios. A number of writers, this reviewer included, have found it difficult to see what practical ethical guidance is available to the ordinary man in the egoistic behaviour of the Plotinian spoudaios. Yet Porphyry's Life presents Plotinus, whom one must assume was a spoudaios, as a figure deeply involved with the life of the community and not the austere figure that the Enneads seem to conjure up. S claims that this dichotomy can be resolved upon examination of the figure of the spoudaios, and in the seven chapters that make up this monograph, she argues her case in a thorough and scholarly manner

Time for the Child Tax Credit to Grow Up: Preserving the Credit’s Availability and Enhancing Benefits for Families

The Child Tax Credit is one of the largest subsidies in the tax code for families with children. The CTC provides a supplementary boost to families by providing cash income when they do not have income tax liability. The CTC has more recently been used as an economic recovery measure and as a work incentive. However, the Credit’s own structure undermines its ability to serve these purposes. The Credit should be structured such that it will further the program’s key purposes and remain available to more low- income families. Some beneficial structural changes include permanently setting the refundability threshold at $3,000 and insulating the Credit’s provisions from inflation

Alexandrine Schniewind: L'Ethique du Sage chez Plotin. Le paradigme du spoudaios.

The focus of this monograph is, as its title suggests, the ethical stance of the spoudaios in Plotinus' Enneads. Schniewind, hereafter S, provides in her introduction an accurate summary of the work of previous writers on Plotinus' ethical theory. This summary demonstrates that there is some disagreement as to whether or not Plotinus provides an ethic that is applicable to the ordinary man, as opposed to the spoudaios. A number of writers, this reviewer included, have found it difficult to see what practical ethical guidance is available to the ordinary man in the egoistic behaviour of the Plotinian spoudaios. Yet Porphyry's Life presents Plotinus, whom one must assume was a spoudaios, as a figure deeply involved with the life of the community and not the austere figure that the Enneads seem to conjure up. S claims that this dichotomy can be resolved upon examination of the figure of the spoudaios, and in the seven chapters that make up this monograph, she argues her case in a thorough and scholarly manner

The Ethics of Plotinus

The theme of this paper is, what I believe to be, the inconsistency in the life lived by Plotinus and the ethical teaching of the Enneads. This paper will do little more than set out the problem. We know quite a bit about the life Plotinus lived because of a biography written by his most famous pupil, Porphyry. We have some fragments from another biogra~hy by Eunapius and other bits and pieces. But Porphyry is the chief source. We are lucky to have anything at all when we consider the opening lines of Porphyry's biography: Plotinus, the philosopher of our times, seemed ashamed of being in the body. As a result of this state of mind he could never bear to talk about his race or his parents or his native country (Vita Plotini 1.1-2)

The Ethics of Plotinus

The theme of this paper is, what I believe to be, the inconsistency in the life lived by Plotinus and the ethical teaching of the Enneads. This paper will do little more than set out the problem. We know quite a bit about the life Plotinus lived because of a biography written by his most famous pupil, Porphyry. We have some fragments from another biogra~hy by Eunapius and other bits and pieces. But Porphyry is the chief source. We are lucky to have anything at all when we consider the opening lines of Porphyry's biography: Plotinus, the philosopher of our times, seemed ashamed of being in the body. As a result of this state of mind he could never bear to talk about his race or his parents or his native country (Vita Plotini 1.1-2)

Did Alexander the Great read Xenophon?

It has been assumed by writers, ancient and modern, that Xenophon’s literary output had a direct influence on Alexander the Great. But is there any evidence to prove that it did? In spite of the paucity of references to Xenophon in the surviving Alexander sources, many writers, both ancient and modern, have no doubts concerning the influence of Xenophon’s writings on Alexander. An extreme position is suggested by Eunapius, the sophist and historian born at Sardis c. AD 345, when he says in his Lives of the Sophists (VS I, 453): ‘Alexander the Great would not have become great if there had been no Xenophon’. However, Eunapius might mean little more than Alexander had heard of, and been inspired by, what Xenophon had done in Asia. We are looking for evidence that Alexander had read Xenophon; most modern literature is in no doubt that he did. Almost all the major monographs on Alexander, those by Wilcken, Robinson, Tarn, Hammond and Lane Fox, among others, take it for granted that Alexander had read and learned from Xenophon