2,253 research outputs found
Optimal Inference in Crowdsourced Classification via Belief Propagation
Crowdsourcing systems are popular for solving large-scale labelling tasks
with low-paid workers. We study the problem of recovering the true labels from
the possibly erroneous crowdsourced labels under the popular Dawid-Skene model.
To address this inference problem, several algorithms have recently been
proposed, but the best known guarantee is still significantly larger than the
fundamental limit. We close this gap by introducing a tighter lower bound on
the fundamental limit and proving that Belief Propagation (BP) exactly matches
this lower bound. The guaranteed optimality of BP is the strongest in the sense
that it is information-theoretically impossible for any other algorithm to
correctly label a larger fraction of the tasks. Experimental results suggest
that BP is close to optimal for all regimes considered and improves upon
competing state-of-the-art algorithms.Comment: This article is partially based on preliminary results published in
the proceeding of the 33rd International Conference on Machine Learning (ICML
2016
A Currency Union in East Asia
This paper investigates prospects of a currency union in East Asia, focusing on trade and financial integration occurring in the region. We find, based on a dynamic factor model, regional common shocks have been quantitatively important for output variations in the Asian economies. We expect that continuing trade integration in the region will lead to further synchronization of business cycles, thereby encouraging East Asian countries to create a currency union in the region. In contrast to trade, however, financial liberalization in East Asia tends to lead to more global integration, rather than regional integration, of the financial systems, and thereby is not likely to develop favorable conditions for forming a regional currency union among East Asian countries.
Embedding of Virtual Network Requests over Static Wireless Multihop Networks
Network virtualization is a technology of running multiple heterogeneous
network architecture on a shared substrate network. One of the crucial
components in network virtualization is virtual network embedding, which
provides a way to allocate physical network resources (CPU and link bandwidth)
to virtual network requests. Despite significant research efforts on virtual
network embedding in wired and cellular networks, little attention has been
paid to that in wireless multi-hop networks, which is becoming more important
due to its rapid growth and the need to share these networks among different
business sectors and users. In this paper, we first study the root causes of
new challenges of virtual network embedding in wireless multi-hop networks, and
propose a new embedding algorithm that efficiently uses the resources of the
physical substrate network. We examine our algorithm's performance through
extensive simulations under various scenarios. Due to lack of competitive
algorithms, we compare the proposed algorithm to five other algorithms, mainly
borrowed from wired embedding or artificially made by us, partially with or
without the key algorithmic ideas to assess their impacts.Comment: 22 page
Iterative Bayesian Learning for Crowdsourced Regression
Crowdsourcing platforms emerged as popular venues for purchasing human
intelligence at low cost for large volume of tasks. As many low-paid workers
are prone to give noisy answers, a common practice is to add redundancy by
assigning multiple workers to each task and then simply average out these
answers. However, to fully harness the wisdom of the crowd, one needs to learn
the heterogeneous quality of each worker. We resolve this fundamental challenge
in crowdsourced regression tasks, i.e., the answer takes continuous labels,
where identifying good or bad workers becomes much more non-trivial compared to
a classification setting of discrete labels. In particular, we introduce a
Bayesian iterative scheme and show that it provably achieves the optimal mean
squared error. Our evaluations on synthetic and real-world datasets support our
theoretical results and show the superiority of the proposed scheme
Laser-assisted microchanneling on PMMA substrate utilizing two-pass fabrication method
Microchannel is widely used in microfluidic devices for mixing, chemical reaction, detection, particle separation and etc. CO2 laser-based microchanneling of PMMA as a low cost, rapid, noncontact fabrication method has attracted the attention of industry. However, the typical V-shape grooves fabricated by CO2 laser microchanneling have limitations since the V-shape grooves will affect the flow behavior and heat transfer of the fluid, which are important to the performance of microfluidic devices. A two-pass fabrication method is proposed and investigated in this paper to improve the quality of the PMMA microchannel fabricated by CO2 laser. It was found that by using this method, a trapezoidal shape groove can be formed. Such a microchannel is of higher quality compared with the V-shape groove microchannel
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