11,892 research outputs found
Finitely additive beliefs and universal type spaces
The probabilistic type spaces in the sense of Harsanyi [Management Sci. 14
(1967/68) 159--182, 320--334, 486--502] are the prevalent models used to
describe interactive uncertainty. In this paper we examine the existence of a
universal type space when beliefs are described by finitely additive
probability measures. We find that in the category of all type spaces that
satisfy certain measurability conditions (-measurability, for some
fixed regular cardinal ), there is a universal type space (i.e., a
terminal object) to which every type space can be mapped in a unique
beliefs-preserving way. However, by a probabilistic adaption of the elegant
sober-drunk example of Heifetz and Samet [Games Econom. Behav. 22 (1998)
260--273] we show that if all subsets of the spaces are required to be
measurable, then there is no universal type space.Comment: Published at http://dx.doi.org/10.1214/009117905000000576 in the
Annals of Probability (http://www.imstat.org/aop/) by the Institute of
Mathematical Statistics (http://www.imstat.org
A new strategy for Robbins' problem of optimal stopping
In this article we study the expected rank problem under full information.
Our approach uses the planar Poisson approach from Gnedin (2007) to derive the
expected rank of a stopping rule that is one of the simplest non-trivial
examples combining rank dependent rules with threshold rules. This rule attains
an expected rank lower than the best upper bounds obtained in the literature so
far, in particular we obtain an expected rank of 2.32614
LTL Fragments are Hard for Standard Parameterisations
We classify the complexity of the LTL satisfiability and model checking
problems for several standard parameterisations. The investigated parameters
are temporal depth, number of propositional variables and formula treewidth,
resp., pathwidth. We show that all operator fragments of LTL under the
investigated parameterisations are intractable in the sense of parameterised
complexity.Comment: TIME 2015 conference versio
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