2,599 research outputs found

    LIPIcs, Volume 251, ITCS 2023, Complete Volume

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    LIPIcs, Volume 251, ITCS 2023, Complete Volum

    Autobidders with Budget and ROI Constraints: Efficiency, Regret, and Pacing Dynamics

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    We study a game between autobidding algorithms that compete in an online advertising platform. Each autobidder is tasked with maximizing its advertiser's total value over multiple rounds of a repeated auction, subject to budget and/or return-on-investment constraints. We propose a gradient-based learning algorithm that is guaranteed to satisfy all constraints and achieves vanishing individual regret. Our algorithm uses only bandit feedback and can be used with the first- or second-price auction, as well as with any "intermediate" auction format. Our main result is that when these autobidders play against each other, the resulting expected liquid welfare over all rounds is at least half of the expected optimal liquid welfare achieved by any allocation. This holds whether or not the bidding dynamics converges to an equilibrium and regardless of the correlation structure between advertiser valuations

    Learning in Repeated Multi-Unit Pay-As-Bid Auctions

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    Motivated by Carbon Emissions Trading Schemes, Treasury Auctions, and Procurement Auctions, which all involve the auctioning of homogeneous multiple units, we consider the problem of learning how to bid in repeated multi-unit pay-as-bid auctions. In each of these auctions, a large number of (identical) items are to be allocated to the largest submitted bids, where the price of each of the winning bids is equal to the bid itself. The problem of learning how to bid in pay-as-bid auctions is challenging due to the combinatorial nature of the action space. We overcome this challenge by focusing on the offline setting, where the bidder optimizes their vector of bids while only having access to the past submitted bids by other bidders. We show that the optimal solution to the offline problem can be obtained using a polynomial time dynamic programming (DP) scheme. We leverage the structure of the DP scheme to design online learning algorithms with polynomial time and space complexity under full information and bandit feedback settings. We achieve an upper bound on regret of O(MTlogB)O(M\sqrt{T\log |\mathcal{B}|}) and O(MBTlogB)O(M\sqrt{|\mathcal{B}|T\log |\mathcal{B}|}) respectively, where MM is the number of units demanded by the bidder, TT is the total number of auctions, and B|\mathcal{B}| is the size of the discretized bid space. We accompany these results with a regret lower bound, which match the linear dependency in MM. Our numerical results suggest that when all agents behave according to our proposed no regret learning algorithms, the resulting market dynamics mainly converge to a welfare maximizing equilibrium where bidders submit uniform bids. Lastly, our experiments demonstrate that the pay-as-bid auction consistently generates significantly higher revenue compared to its popular alternative, the uniform price auction.Comment: 51 pages, 12 Figure

    Ethnographies of Collaborative Economies across Europe: Understanding Sharing and Caring

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    "Sharing economy" and "collaborative economy" refer to a proliferation of initiatives, business models, digital platforms and forms of work that characterise contemporary life: from community-led initiatives and activist campaigns, to the impact of global sharing platforms in contexts such as network hospitality, transportation, etc. Sharing the common lens of ethnographic methods, this book presents in-depth examinations of collaborative economy phenomena. The book combines qualitative research and ethnographic methodology with a range of different collaborative economy case studies and topics across Europe. It uniquely offers a truly interdisciplinary approach. It emerges from a unique, long-term, multinational, cross-European collaboration between researchers from various disciplines (e.g., sociology, anthropology, geography, business studies, law, computing, information systems), career stages, and epistemological backgrounds, brought together by a shared research interest in the collaborative economy. This book is a further contribution to the in-depth qualitative understanding of the complexities of the collaborative economy phenomenon. These rich accounts contribute to the painting of a complex landscape that spans several countries and regions, and diverse political, cultural, and organisational backdrops. This book also offers important reflections on the role of ethnographic researchers, and on their stance and outlook, that are of paramount interest across the disciplines involved in collaborative economy research

    Games with Trading of Control

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    The Material Culture of Freemasonry:A Part of Things not a Thing Apart

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    Freemasonry is often seen as 'a thing apart' rather than 'a part of things'. This thesis applies well-established anthropological and sociological theories to the material culture of freemasonry, in particular Actor Network Theory. It establishes for the first time that this method binds freemasonry into the broader world of material culture and also provides unexpected insights into freemasonry itself.Centering the examination on my personal experience as Curator at the Museum of Freemasonry in London I consider how the collecting and display or failure to display objects used by, created by and commercially produced for freemasons provides insights in the round on how the material is regarded by society. The perceived secrecy of freemasonry is considered and I show that this is a contested and variable boundary between concealment and revelation. Most of the information needed to study the material culture of freemasonry is accessible to external researchers.I establish the nature of these objects and the way in which the inanimate material culture of freemasonry has innate properties that generate affect and agency on the freemasons and wider society. I show how this material culture is bound into the development of capitalism and consumerism from the early eighteenth century onwards. It forms the first and only continuous example of identity supporting material culture to arise ex nihilo and develop in parallel with the consumer society from the early eighteenth century. This has strong parallels with later material cultures reinforcing identity but is the paradigm and key point for comparison.I view freemasonry's material culture from different viewpoints, firstly its development and relevance to freemasons then establishing its relationship with the broader non-masonic world. I then de-contextualise it by examining its role as collectable giving the material a new agency not always related to its intended function or meaning.The thesis establishes for the first time that masonic material culture has a meaning and significance beyond the specifics of freemasonry studies. I show that a wide range of theories can be brought to bear on this topic and argue that there are multiple significant additional routes to study that have yet to be investigated.I conclude that the material culture of freemasonry is indeed 'a part of things' and if as researchers we fail to investigate the 'things' that freemasonry creates we lose a significant tool to investigate and analyse freemasonry as part of the wider social and anthropological world

    Metaverse. Old urban issues in new virtual cities

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    Recent years have seen the arise of some early attempts to build virtual cities, utopias or affective dystopias in an embodied Internet, which in some respects appear to be the ultimate expression of the neoliberal city paradigma (even if virtual). Although there is an extensive disciplinary literature on the relationship between planning and virtual or augmented reality linked mainly to the gaming industry, this often avoids design and value issues. The observation of some of these early experiences - Decentraland, Minecraft, Liberland Metaverse, to name a few - poses important questions and problems that are gradually becoming inescapable for designers and urban planners, and allows us to make some partial considerations on the risks and potentialities of these early virtual cities

    Demand Response in Smart Grids

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    The Special Issue “Demand Response in Smart Grids” includes 11 papers on a variety of topics. The success of this Special Issue demonstrates the relevance of demand response programs and events in the operation of power and energy systems at both the distribution level and at the wide power system level. This reprint addresses the design, implementation, and operation of demand response programs, with focus on methods and techniques to achieve an optimized operation as well as on the electricity consumer
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