20,402 research outputs found
Fast Differentially Private Matrix Factorization
Differentially private collaborative filtering is a challenging task, both in
terms of accuracy and speed. We present a simple algorithm that is provably
differentially private, while offering good performance, using a novel
connection of differential privacy to Bayesian posterior sampling via
Stochastic Gradient Langevin Dynamics. Due to its simplicity the algorithm
lends itself to efficient implementation. By careful systems design and by
exploiting the power law behavior of the data to maximize CPU cache bandwidth
we are able to generate 1024 dimensional models at a rate of 8.5 million
recommendations per second on a single PC
A Comparative Study of Pairwise Learning Methods based on Kernel Ridge Regression
Many machine learning problems can be formulated as predicting labels for a
pair of objects. Problems of that kind are often referred to as pairwise
learning, dyadic prediction or network inference problems. During the last
decade kernel methods have played a dominant role in pairwise learning. They
still obtain a state-of-the-art predictive performance, but a theoretical
analysis of their behavior has been underexplored in the machine learning
literature.
In this work we review and unify existing kernel-based algorithms that are
commonly used in different pairwise learning settings, ranging from matrix
filtering to zero-shot learning. To this end, we focus on closed-form efficient
instantiations of Kronecker kernel ridge regression. We show that independent
task kernel ridge regression, two-step kernel ridge regression and a linear
matrix filter arise naturally as a special case of Kronecker kernel ridge
regression, implying that all these methods implicitly minimize a squared loss.
In addition, we analyze universality, consistency and spectral filtering
properties. Our theoretical results provide valuable insights in assessing the
advantages and limitations of existing pairwise learning methods.Comment: arXiv admin note: text overlap with arXiv:1606.0427
Peer-to-Peer Secure Multi-Party Numerical Computation Facing Malicious Adversaries
We propose an efficient framework for enabling secure multi-party numerical
computations in a Peer-to-Peer network. This problem arises in a range of
applications such as collaborative filtering, distributed computation of trust
and reputation, monitoring and other tasks, where the computing nodes is
expected to preserve the privacy of their inputs while performing a joint
computation of a certain function. Although there is a rich literature in the
field of distributed systems security concerning secure multi-party
computation, in practice it is hard to deploy those methods in very large scale
Peer-to-Peer networks. In this work, we try to bridge the gap between
theoretical algorithms in the security domain, and a practical Peer-to-Peer
deployment.
We consider two security models. The first is the semi-honest model where
peers correctly follow the protocol, but try to reveal private information. We
provide three possible schemes for secure multi-party numerical computation for
this model and identify a single light-weight scheme which outperforms the
others. Using extensive simulation results over real Internet topologies, we
demonstrate that our scheme is scalable to very large networks, with up to
millions of nodes. The second model we consider is the malicious peers model,
where peers can behave arbitrarily, deliberately trying to affect the results
of the computation as well as compromising the privacy of other peers. For this
model we provide a fourth scheme to defend the execution of the computation
against the malicious peers. The proposed scheme has a higher complexity
relative to the semi-honest model. Overall, we provide the Peer-to-Peer network
designer a set of tools to choose from, based on the desired level of security.Comment: Submitted to Peer-to-Peer Networking and Applications Journal (PPNA)
200
Structuring Wikipedia Articles with Section Recommendations
Sections are the building blocks of Wikipedia articles. They enhance
readability and can be used as a structured entry point for creating and
expanding articles. Structuring a new or already existing Wikipedia article
with sections is a hard task for humans, especially for newcomers or less
experienced editors, as it requires significant knowledge about how a
well-written article looks for each possible topic. Inspired by this need, the
present paper defines the problem of section recommendation for Wikipedia
articles and proposes several approaches for tackling it. Our systems can help
editors by recommending what sections to add to already existing or newly
created Wikipedia articles. Our basic paradigm is to generate recommendations
by sourcing sections from articles that are similar to the input article. We
explore several ways of defining similarity for this purpose (based on topic
modeling, collaborative filtering, and Wikipedia's category system). We use
both automatic and human evaluation approaches for assessing the performance of
our recommendation system, concluding that the category-based approach works
best, achieving precision@10 of about 80% in the human evaluation.Comment: SIGIR '18 camera-read
Self-stabilizing Numerical Iterative Computation
Many challenging tasks in sensor networks, including sensor calibration,
ranking of nodes, monitoring, event region detection, collaborative filtering,
collaborative signal processing, {\em etc.}, can be formulated as a problem of
solving a linear system of equations. Several recent works propose different
distributed algorithms for solving these problems, usually by using linear
iterative numerical methods.
In this work, we extend the settings of the above approaches, by adding
another dimension to the problem. Specifically, we are interested in {\em
self-stabilizing} algorithms, that continuously run and converge to a solution
from any initial state. This aspect of the problem is highly important due to
the dynamic nature of the network and the frequent changes in the measured
environment.
In this paper, we link together algorithms from two different domains. On the
one hand, we use the rich linear algebra literature of linear iterative methods
for solving systems of linear equations, which are naturally distributed with
rapid convergence properties. On the other hand, we are interested in
self-stabilizing algorithms, where the input to the computation is constantly
changing, and we would like the algorithms to converge from any initial state.
We propose a simple novel method called \syncAlg as a self-stabilizing variant
of the linear iterative methods. We prove that under mild conditions the
self-stabilizing algorithm converges to a desired result. We further extend
these results to handle the asynchronous case.
As a case study, we discuss the sensor calibration problem and provide
simulation results to support the applicability of our approach
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