476 research outputs found
In Broad Daylight: Fuller Information and Higher-Order Punishment Opportunities Can Promote Cooperation
The expectation that non-cooperators will be punished can help to sustain cooperation, but there are competing claims about whether opportunities to engage in higher-order punishment (punishing punishment or failure to punish) help or undermine cooperation in social dilemmas. Varying treatments of a voluntary contributions experiment, we find that availability of higher-order punishment opportunities increases cooperation and efficiency when subjects have full information on the pattern of punishing and its history, when any subject can punish any other, and when the numbers of punishment and of contribution stages are not too unequal
Play it Again: Partner Choice, Reputation Building and Learning from Finitely-Repeated Dilemma Games
Often the fuller the reputational record people's actions generate, the greater their incentive to earn a reputation for cooperation. However, inability to “wipe clean” one's past record might trap some agents who initially underappreciate reputation's value in a cycle of bad behaviour, whereas a clean slate could have been followed by their “reforming” themselves. In a laboratory experiment, we investigate what subjects learn from playing a finitely repeated dilemma game with endogenous, symmetric partner choice. We find that with a high cooperation premium and good information, investment in cooperative reputation grows following exogenous restarts, although earlier end-game behaviours are observed
Pseudorandom Linear Codes are List Decodable to Capacity
We introduce a novel family of expander-based error correcting codes. These
codes can be sampled with randomness linear in the block-length, and achieve
list-decoding capacity (among other local properties). Our expander-based codes
can be made starting from any family of sufficiently low-bias codes, and as a
consequence, we give the first construction of a family of algebraic codes that
can be sampled with linear randomness and achieve list-decoding capacity. We
achieve this by introducing the notion of a pseudorandom puncturing of a code,
where we select indices of a base code via an
expander random walk on a graph on . Concretely, whereas a random linear
code (i.e. a truly random puncturing of the Hadamard code) requires
random bits to sample, we sample a pseudorandom linear code with random
bits. We show that pseudorandom puncturings satisfy several desirable
properties exhibited by truly random puncturings. In particular, we extend a
result of (Guruswami Mosheiff FOCS 2022) and show that a pseudorandom
puncturing of a small-bias code satisfies the same local properties as a random
linear code with high probability. As a further application of our techniques,
we also show that pseudorandom puncturings of Reed Solomon codes are
list-recoverable beyond the Johnson bound, extending a result of (Lund
Potukuchi RANDOM 2020). We do this by instead analyzing properties of codes
with large distance, and show that pseudorandom puncturings still work well in
this regime.Comment: Fixed author nam
State or nature? Endogenous formal versus informal sanctions in the voluntary provision of public goods
We investigate the endogenous formation of sanctioning institutions supposed to improve efficiency in the voluntary provision of public goods. Our paper parallels Markussen et al. (Rev Econ Stud 81:301–324, 2014) in that our experimental subjects vote over formal versus informal sanctions, but it goes beyond that paper by endogenizing the formal sanction scheme. We find that self-determined formal sanctions schemes are popular and efficient when they carry no up-front cost, but as in Markussen et al. informal sanctions are more popular and efficient than formal sanctions when adopting the latter entails such a cost. Practice improves the performance of sanction schemes: they become more targeted and deterrent with learning. Voters’ characteristics, including their tendency to engage in perverse informal sanctioning, help to predict individual voting
Damping of sound waves in superfluid nucleon-hyperon matter of neutron stars
We consider sound waves in superfluid nucleon-hyperon matter of massive
neutron-star cores. We calculate and analyze the speeds of sound modes and
their damping times due to the shear viscosity and non-equilibrium weak
processes of particle transformations. For that, we employ the dissipative
relativistic hydrodynamics of a superfluid nucleon-hyperon mixture, formulated
recently [M.E. Gusakov and E.M. Kantor, Phys. Rev. D78, 083006 (2008)]. We
demonstrate that the damping times of sound modes calculated using this
hydrodynamics and the ordinary (nonsuperfluid) one, can differ from each other
by several orders of magnitude.Comment: 15 pages, 5 figures, Phys. Rev. D accepte
Transport coefficients from the Boson Uehling-Uhlenbeck Equation
We derive microscopic expressions for the bulk viscosity, shear viscosity and
thermal conductivity of a quantum degenerate Bose gas above , the critical
temperature for Bose-Einstein condensation. The gas interacts via a contact
potential and is described by the Uehling-Uhlenbeck equation. To derive the
transport coefficients, we use Rayleigh-Schrodinger perturbation theory rather
than the Chapman-Enskog approach. This approach illuminates the link between
transport coefficients and eigenvalues of the collision operator. We find that
a method of summing the second order contributions using the fact that the
relaxation rates have a known limit improves the accuracy of the computations.
We numerically compute the shear viscosity and thermal conductivity for any
boson gas that interacts via a contact potential. We find that the bulk
viscosity remains identically zero as it is for the classical case.Comment: 10 pages, 2 figures, submitted to Phys. Rev.
- …