Une classification des hypothèses calculatoire dans le modèle du groupe algébrique

International audiencea We give a taxonomy of computational assumptions in the algebraic group model (AGM). We first analyze Boyen's Uber assumption family for bilinear groups and then extend it in several ways to cover assumptions as diverse as Gap Diffie-Hellman and LRSW. We show that in the AGM every member of these families is implied by the q-discrete logarithm (DL) assumption, for some q that depends on the degrees of the polynomials defining the Uber assumption. Using the meta-reduction technique, we then separate (q + 1)-DL from q-DL, which yields a classification of all members of the extended Uber-assumption families. We finally show that there are strong assumptions, such as one-more DL, that provably fall outside our classification, by proving that they cannot be reduced from q-DL even in the AGM

The Uber-Knowledge Assumption: A Bridge to the AGM

The generic-group model (GGM) and the algebraic-group model (AGM) have been immensely successful in proving the security of many classical and modern cryptosystems. These models, however, come coupled with standard-model uninstantiability results, raising the question whether the schemes analyzed under them can be based on firmer standard-model footing. We formulate the uber-knowledge (UK) assumption, a standard-model assumption that naturally extends the uber-assumption family to knowledge assumptions. We justify the soundness of the UK in both the bilinear GGM and bilinear AGM. Along the way we extend these models to incorporate hashing into groups, an adversarial capability that is available in many concrete groups. (In contrast to standard assumptions, hashing may affect the validity of knowledge assumptions.) These results, in turn, enable a modular approach to security in GGM and AGM. As example applications, we use the UK to prove knowledge-soundness of Groth16 and KZG polynomial commitments in the standard model, where for the former we reuse the existing AGM proof without hashing

Uber Effort: The Production of Worker Consent in Online Ride Sharing Platforms

The rise of the online gig economy alters ways of working. Mediated by algorithmically programmed mobile apps, platforms such as Uber and Lyft allow workers to work by driving and completing rides at any time or in any place that the drivers choose. This hybrid form of labor in an online gig economy which combines independent contract work with computer-mediated work differs from traditional manufacturing jobs in both its production activity and production relations. Through nine interviews with Lyft/Uber drivers, I found that workers’ consent, which was first articulated by Michael Burawoy in the context of the manufacturing economy, is still present in the work of the online gig economy in post-industrial capitalism. Workers willingly engage in the on-demand work not only to earn money but also to play a learning game motivated by the ambiguity of the management system, in which process they earn a sense of self-satisfaction and an illusion of autonomous control. This research points to the important role of technology in shaping contemporary labor process and suggests the potential mechanism which produces workers’ consent in technology-driven workplaces

Coexistence in locally regulated competing populations and survival of branching annihilating random walk

We propose two models of the evolution of a pair of competing populations. Both are lattice based. The first is a compromise between fully spatial models, which do not appear amenable to analytic results, and interacting particle system models, which do not, at present, incorporate all of the competitive strategies that a population might adopt. The second is a simplification of the first, in which competition is only supposed to act within lattice sites and the total population size within each lattice point is a constant. In a special case, this second model is dual to a branching annihilating random walk. For each model, using a comparison with oriented percolation, we show that for certain parameter values, both populations will coexist for all time with positive probability. As a corollary, we deduce survival for all time of branching annihilating random walk for sufficiently large branching rates. We also present a number of conjectures relating to the r\^{o}le of space in the survival probabilities for the two populations.Comment: Published in at http://dx.doi.org/10.1214/105051607000000267 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Gender Equality in Virtual Work I.: Risks

This article focuses on gender equality in virtual work, taking special account of the regulatory challenges. It contributes to broader debates on the workers' situation in the sharing economy in two ways. Firstly, it makes an inaugural attempt to evaluate the implications of the new forms of work in the sharing economy for female virtual workers, looking at the issue of equal treatment. Secondly, it offers preliminary suggestions regarding a future regulation to improve equality between genders in virtual work. The paper is divided into four main parts. The first section defines "virtual work", classifies its two basic forms and emphasises the specific traits of this form of work to demonstrate the need of special protection against discrimination. Secondly, the paper identifies the possible beneficial and adverse implications of virtual work for female workers and gender equality. Thirdly, the paper provides a summary of the gender equality law of the European Union that serves as a point of reference when speaking about antidiscrimination law. Section 4 offers three normative perspectives and suggestions as to how to enhance gender equality in virtual work. Finally, the paper concludes. This first part of this two-part paper concentrates on the risks of virtual work for equal treatment, while the second part is going to address the regulatory options and suggestions

Gender Equality in Virtual Work II.: Regulatory Suggestions

This article focuses on gender equality in virtual work, taking special account of the regulatory challenges. It contributes to broader debates on the workers' situation in the sharing economy in two ways. Firstly, it makes an inaugural attempt to evaluate the implications of the new forms of work in the sharing economy for female virtual workers, looking at the issue of equal treatment. Secondly, it offers preliminary suggestions regarding a future regulation to improve equality between genders in virtual work. This is the second part of a paper on gender equality in virtual work. The first part (published in the 2018/1 issue of the Hungarian Labour Law E-Journal) defined "virtual work", classified its two basic forms and emphasised the specific traits of this form of work to demonstrate the need of special protection against discrimination. Subsequently, it identified the possible beneficial and adverse implications of virtual work for female workers and gender equality. This second part firstly provides a summary of the gender equality law of the European Union that serves as a point of reference when speaking about antidiscrimination law. Section 2 offers three normative perspectives and suggestions as to how to enhance gender equality in virtual work. Finally, the paper concludes

Grade Inflation, Social Background, and Labour Market Matching

A model is presented where workers of differing abilities and from different social backgrounds are assigned to jobs based on grades received at school. It is examined how this matching is affected if good grades are granted to some low ability students. Such grade inflation is shown to reduce the aggregate wage of the lower class workers because employers use social origin as a signal for productivity if grades are less than fully informative. Moreover, the high-ability students from the higher class may benefit from grade inflation since this shields them from the competition on the part of able students from the lower classes. --education,grading,standards,assignment,social mobility,grading,standards,assignment,social mobility