153 research outputs found
Fair Artificial Currency Incentives in Repeated Weighted Congestion Games: Equity vs. Equality
When users access shared resources in a selfish manner, the resulting
societal cost and perceived users' cost is often higher than what would result
from a centrally coordinated optimal allocation. While several contributions in
mechanism design manage to steer the aggregate users choices to the desired
optimum by using monetary tolls, such approaches bear the inherent drawback of
discriminating against users with a lower income. More recently, incentive
schemes based on artificial currencies have been studied with the goal of
achieving a system-optimal resource allocation that is also fair. In this
resource-sharing context, this paper focuses on repeated weighted congestion
game with two resources, where users contribute to the congestion to different
extents that are captured by individual weights. First, we address the broad
concept of fairness by providing a rigorous mathematical characterization of
the distinct societal metrics of equity and equality, i.e., the concepts of
providing equal outcomes and equal opportunities, respectively. Second, we
devise weight-dependent and time-invariant optimal pricing policies to maximize
equity and equality, and prove convergence of the aggregate user choices to the
system-optimum. In our framework it is always possible to achieve
system-optimal allocations with perfect equity, while the maximum equality that
can be reached may not be perfect, which is also shown via numerical
simulations
Urgency-aware Optimal Routing in Repeated Games through Artificial Currencies
When people choose routes minimizing their individual delay, the aggregate
congestion can be much higher compared to that experienced by a
centrally-imposed routing. Yet centralized routing is incompatible with the
presence of self-interested agents. How can we reconcile the two? In this paper
we address this question within a repeated game framework and propose a fair
incentive mechanism based on artificial currencies that routes selfish agents
in a system-optimal fashion, while accounting for their temporal preferences.
We instantiate the framework in a parallel-network whereby agents commute
repeatedly (e.g., daily) from a common start node to the end node. Thereafter,
we focus on the specific two-arcs case whereby, based on an artificial
currency, the agents are charged when traveling on the first, fast arc, whilst
they are rewarded when traveling on the second, slower arc. We assume the
agents to be rational and model their choices through a game where each agent
aims at minimizing a combination of today's discomfort, weighted by their
urgency, and the average discomfort encountered for the rest of the period
(e.g., a week). We show that, if prices of artificial currencies are
judiciously chosen, the routing pattern converges to a system-optimal solution,
while accommodating the agents' urgency. We complement our study through
numerical simulations. Our results show that it is possible to achieve a
system-optimal solution whilst reducing the agents' perceived discomfort by
14-20% when compared to a centralized optimal but urgency-unaware policy.Comment: Accepted for presentation at the European Control Conference 202
Urgency-aware optimal routing in repeated games through artificial currencies
When people choose routes minimizing their individual delay, the aggregate congestion can be much higher compared to that experienced by a centrally-imposed routing. Yet centralized routing is incompatible with the presence of self-interested users. How can we reconcile the two? In this paper we address this question within a repeated game framework and propose a fair incentive mechanism based on artificial currencies that routes selfish users in a system-optimal fashion, while accounting for their temporal preferences. We instantiate the framework in a parallel-network whereby users commute repeatedly (e.g., daily) from a common start node to the end node. Thereafter, we focus on the specific two-arcs case whereby, based on an artificial currency, the users are charged when traveling on the first, fast arc, whilst they are rewarded when traveling on the second, slower arc. We assume the users to be rational and model their choices through a game where each user aims at minimizing a combination of today's discomfort, weighted by their urgency, and the average discomfort encountered for the rest of the period (e.g., a week). We show that, if prices of artificial currencies are judiciously chosen, the routing pattern converges to a system-optimal solution, while accommodating the users’ urgency. We complement our study through numerical simulations. Our results show that it is possible to achieve a system-optimal solution whilst significantly reducing the users’ perceived discomfort when compared to a centralized optimal but urgency-unaware policy
Energy Migration Governs Upconversion Losses in Er<sup>3+</sup>-doped Integrated Amplifiers
At high Er3+ doping, electric dipole-dipole interactions between neighboring ions such as energy migration and energy-transfer upconversion (ETU) take place, thereby reducing the population inversion and negatively affecting the gain performance of the amplifier. These effects are investigated by lifetime and gain measurements respectively, in Al2O3:Er3+ waveguides and analyzed the results in the frame of the microscopic model developed by Zubenko et al
Realism and the wave-function
Realism -- the idea that the concepts in physical theories refer to 'things'
existing in the real world -- is introduced as a tool to analyze the status of
the wave-function. Although the physical entities are recognized by the
existence of invariant quantities, examples from classical and quantum physics
suggest that not all the theoretical terms refer to the entities: some terms
refer to properties of the entities, and some terms have only an epistemic
function. In particular, it is argued that the wave-function may be written in
terms of classical non-referring and epistemic terms. The implications for
realist interpretations of quantum mechanics and on the teaching of quantum
physics are examined.Comment: No figure
Abelian gauge potentials on cubic lattices
The study of the properties of quantum particles in a periodic potential
subject to a magnetic field is an active area of research both in physics and
mathematics; it has been and it is still deeply investigated. In this review we
discuss how to implement and describe tunable Abelian magnetic fields in a
system of ultracold atoms in optical lattices. After discussing two of the main
experimental schemes for the physical realization of synthetic gauge potentials
in ultracold set-ups, we study cubic lattice tight-binding models with
commensurate flux. We finally examine applications of gauge potentials in
one-dimensional rings.Comment: To appear on: "Advances in Quantum Mechanics: Contemporary Trends and
Open Problems", G. Dell'Antonio and A. Michelangeli eds., Springer-INdAM
series 201
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