29,320 research outputs found
A Unified View of Large-scale Zero-sum Equilibrium Computation
The task of computing approximate Nash equilibria in large zero-sum
extensive-form games has received a tremendous amount of attention due mainly
to the Annual Computer Poker Competition. Immediately after its inception, two
competing and seemingly different approaches emerged---one an application of
no-regret online learning, the other a sophisticated gradient method applied to
a convex-concave saddle-point formulation. Since then, both approaches have
grown in relative isolation with advancements on one side not effecting the
other. In this paper, we rectify this by dissecting and, in a sense, unify the
two views.Comment: AAAI Workshop on Computer Poker and Imperfect Informatio
Finite temperature effective theories
Lecture Notes, Summer School on Effective Theories and Fundamental
Interactions, Erice, July 1996. I describe the construction of effective field
theories for equilibrium high-temperature plasma of elementary particles.Comment: 24 pages, Latex, 5 eps figure
Anharmonic stacking in supercoiled DNA
Multistep denaturation in a short circular DNA molecule is analyzed by a
mesoscopic Hamiltonian model which accounts for the helicoidal geometry.
Computation of melting profiles by the path integral method suggests that
stacking anharmonicity stabilizes the double helix against thermal disruption
of the hydrogen bonds. Twisting is essential in the model to capture the
importance of nonlinear effects on the thermodynamical properties. In a ladder
model with zero twist, anharmonic stacking scarcely affects the thermodynamics.
Moderately untwisted helices, with respect to the equilibrium conformation,
show an energetic advantage against the overtwisted ones. Accordingly
moderately untwisted helices better sustain local fluctuational openings and
make more unlikely the thermally driven complete strand separation.Comment: In pres
Theoretical and Practical Advances on Smoothing for Extensive-Form Games
Sparse iterative methods, in particular first-order methods, are known to be
among the most effective in solving large-scale two-player zero-sum
extensive-form games. The convergence rates of these methods depend heavily on
the properties of the distance-generating function that they are based on. We
investigate the acceleration of first-order methods for solving extensive-form
games through better design of the dilated entropy function---a class of
distance-generating functions related to the domains associated with the
extensive-form games. By introducing a new weighting scheme for the dilated
entropy function, we develop the first distance-generating function for the
strategy spaces of sequential games that has no dependence on the branching
factor of the player. This result improves the convergence rate of several
first-order methods by a factor of , where is the branching
factor of the player, and is the depth of the game tree.
Thus far, counterfactual regret minimization methods have been faster in
practice, and more popular, than first-order methods despite their
theoretically inferior convergence rates. Using our new weighting scheme and
practical tuning we show that, for the first time, the excessive gap technique
can be made faster than the fastest counterfactual regret minimization
algorithm, CFR+, in practice
Baryogenesis through leptogenesis
Baryogenesis by heavy-neutrino decay and sphaleron reprocessing of both
baryon and lepton number is reconsidered, paying special attention to the
flavour structure of the general evolution equations and developing an
approximate but sufficiently accurate analytic solution to the prototype
evolution equation. Two different models of neutrino masses are examined, based
on an Abelian U(1) or a non-Abelian U(2) family symmetry. We show that a
consistent picture of baryogenesis can emerge in both cases, although with
significant differences.Comment: 14 pages. v4: revised using the corrected Boltzmann equations of
hep-ph/031012
Electroweak Baryon Number Non-Conservation in the Early Universe and in High Energy Collisions
We review recent progress in the study of the anomalous baryon number
non-conservation at high temperatures and in high energy collisions. Recent
results on high temperature phase transitions are described, and applications
to electroweak baryogenesis are considered. The current status of the problem
of electroweak instanton-like processes at high energies is outlined. This
paper is written on the occasion of Sakharov's 75th anniversary and will appear
in the memorial volume of Uspekhi (Usp. Fiz. Nauk, volume 166, No 5, May 1996).Comment: Minor modifications. A number of new references added. Final version
to appear in Uspekhi (Usp. Fiz. Nauk 166 (May, 1996) No 5). 100 pages and 16
eps figure
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