441 research outputs found
Learning to Play Bayesian Games
This paper discusses the implications of learning theory for the analysis of Bayesian games. One goal is to illuminate the issues that arise when modeling situations where players are learning about the distribution of Nature's move as well as learning about the opponents' strategies. A second goal is to argue that quite restrictive assumptions are necessary to justify the concept of Nash equilibrium without a common prior as a steady state of a learning process.
Two Conditions for Galaxy Quenching: Compact Centres and Massive Haloes
We investigate the roles of two classes of quenching mechanisms for central
and satellite galaxies in the SDSS (): those involving the halo and
those involving the formation of a compact centre. For central galaxies with
inner compactness ,
the quenched fraction is strongly correlated with
with only weak halo mass dependence. However, at higher and lower
, sSFR is a strong function of and mostly
independent of . In other words, divides galaxies into those with high sSFR
below and low sSFR above this range. In both the upper and lower regimes,
increasing shifts the entire sSFR distribtuion to lower sSFR
without a qualitative change in shape. This is true even at fixed , but
varying at fixed adds no quenching information. Most of the
quenched centrals with are dense (), suggesting compaction-related
quenching maintained by halo-related quenching. However, 21% are diffuse,
indicating only halo quenching. For satellite galaxies in the outskirts of
halos, quenching is a strong function of compactness and a weak function of
host . In the inner halo, dominates quenching, with
of the satellites being quenched once . This regional effect is greatest for the least massive
satellites. As demonstrated via semi-analytic modelling with simple
prescriptions for quenching, the observed correlations can be explained if
quenching due to central compactness is rapid while quenching due to halo mass
is slow.Comment: 16 pages, 11 figures, MNRAS accepte
Cool gas accretion, thermal evaporation and quenching of star formation in elliptical galaxies
The most evident features of colour-magnitude diagrams of galaxies are the
red sequence of quiescent galaxies, extending up to the brightest elliptical
galaxies, and the blue cloud of star-forming galaxies, which is truncated at a
luminosity L~L*. The truncation of the blue cloud indicates that in the most
massive systems star formation must be quenched. For this to happen the
virial-temperature galactic gas must be kept hot and any accreted cold gas must
be heated. The elimination of accreted cold gas can be due to thermal
evaporation by the hot interstellar medium, which in turn is prevented from
cooling by feedback from active galactic nuclei.Comment: 2 pages, to appear in Astronomische Nachrichten (proceedings of
Symposium 6 of the JENAM 2008, Vienna
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Subjective Uncertainty Over Behavior Strategies: A Correction
In order to model the subjective uncertainty of a player over the behavior strategies of an opponent, one must consider the player's beliefs about the opponent's play at information sets that the player thinks have probability zero. This corregendum uses “trembles” to provide a definition of the convex hull of a set of behavior strategies. This corrects a definition we gave in [E. Dekel, D. Fudenberg, and D. K. Levine, 1999, J. Econ. Theory 89, 165–185], which led to two of the solution concepts we defined there not having the properties we intended.Economic
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Learning to Play Bayesian Games
This paper discusses the implications of learning theory for the analysis of games with a move by Nature. One goal is to illuminate the issues that arise when modeling situations where players are learning about the distribution of Nature's move as well as learning about the opponents' strategies. A second goal is to argue that quite restrictive assumptions are necessary to justify the concept of Nash equilibrium without a common prior as a steady state of a learning process.Economic
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