119,079 research outputs found
Active Search with a Cost for Switching Actions
Active Sequential Hypothesis Testing (ASHT) is an extension of the classical
sequential hypothesis testing problem with controls. Chernoff (Ann. Math.
Statist., 1959) proposed a policy called Procedure A and showed its asymptotic
optimality as the cost of sampling was driven to zero. In this paper we study a
further extension where we introduce costs for switching of actions. We show
that a modification of Chernoff's Procedure A, one that we call Sluggish
Procedure A, is asymptotically optimal even with switching costs. The growth
rate of the total cost, as the probability of false detection is driven to
zero, and as a switching parameter of the Sluggish Procedure A is driven down
to zero, is the same as that without switching costs.Comment: 8 pages. Presented at 2015 Information Theory and Applications
Worksho
Active Sensing as Bayes-Optimal Sequential Decision Making
Sensory inference under conditions of uncertainty is a major problem in both
machine learning and computational neuroscience. An important but poorly
understood aspect of sensory processing is the role of active sensing. Here, we
present a Bayes-optimal inference and control framework for active sensing,
C-DAC (Context-Dependent Active Controller). Unlike previously proposed
algorithms that optimize abstract statistical objectives such as information
maximization (Infomax) [Butko & Movellan, 2010] or one-step look-ahead accuracy
[Najemnik & Geisler, 2005], our active sensing model directly minimizes a
combination of behavioral costs, such as temporal delay, response error, and
effort. We simulate these algorithms on a simple visual search task to
illustrate scenarios in which context-sensitivity is particularly beneficial
and optimization with respect to generic statistical objectives particularly
inadequate. Motivated by the geometric properties of the C-DAC policy, we
present both parametric and non-parametric approximations, which retain
context-sensitivity while significantly reducing computational complexity.
These approximations enable us to investigate the more complex problem
involving peripheral vision, and we notice that the difference between C-DAC
and statistical policies becomes even more evident in this scenario.Comment: Scheduled to appear in UAI 201
Dataplane Specialization for High-performance OpenFlow Software Switching
OpenFlow is an amazingly expressive dataplane program-
ming language, but this expressiveness comes at a severe
performance price as switches must do excessive packet clas-
sification in the fast path. The prevalent OpenFlow software
switch architecture is therefore built on flow caching, but
this imposes intricate limitations on the workloads that can
be supported efficiently and may even open the door to mali-
cious cache overflow attacks. In this paper we argue that in-
stead of enforcing the same universal flow cache semantics
to all OpenFlow applications and optimize for the common
case, a switch should rather automatically specialize its dat-
aplane piecemeal with respect to the configured workload.
We introduce ES WITCH , a novel switch architecture that
uses on-the-fly template-based code generation to compile
any OpenFlow pipeline into efficient machine code, which
can then be readily used as fast path. We present a proof-
of-concept prototype and we demonstrate on illustrative use
cases that ES WITCH yields a simpler architecture, superior
packet processing speed, improved latency and CPU scala-
bility, and predictable performance. Our prototype can eas-
ily scale beyond 100 Gbps on a single Intel blade even with
complex OpenFlow pipelines
The role of consumers in competition and competition policy
This paper develops the idea that consumers’ behavior matters significantly from the viewpoint of industry performance. This is examined through some theoretical propositions, but then at greater length by means of some case study examples. These examples demonstrate how, even in potentially competitive industries, reluctance on the part of consumers to search or to switch suppliers can lead to a sub-competitive outcome. The significance of non-traditional competition policy remedies in changing the outcome is drawn out.
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