905 research outputs found
A Graphical Model Formulation of Collaborative Filtering Neighbourhood Methods with Fast Maximum Entropy Training
Item neighbourhood methods for collaborative filtering learn a weighted graph
over the set of items, where each item is connected to those it is most similar
to. The prediction of a user's rating on an item is then given by that rating
of neighbouring items, weighted by their similarity. This paper presents a new
neighbourhood approach which we call item fields, whereby an undirected
graphical model is formed over the item graph. The resulting prediction rule is
a simple generalization of the classical approaches, which takes into account
non-local information in the graph, allowing its best results to be obtained
when using drastically fewer edges than other neighbourhood approaches. A fast
approximate maximum entropy training method based on the Bethe approximation is
presented, which uses a simple gradient ascent procedure. When using
precomputed sufficient statistics on the Movielens datasets, our method is
faster than maximum likelihood approaches by two orders of magnitude.Comment: ICML201
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
Addressing Item-Cold Start Problem in Recommendation Systems using Model Based Approach and Deep Learning
Traditional recommendation systems rely on past usage data in order to
generate new recommendations. Those approaches fail to generate sensible
recommendations for new users and items into the system due to missing
information about their past interactions. In this paper, we propose a solution
for successfully addressing item-cold start problem which uses model-based
approach and recent advances in deep learning. In particular, we use latent
factor model for recommendation, and predict the latent factors from item's
descriptions using convolutional neural network when they cannot be obtained
from usage data. Latent factors obtained by applying matrix factorization to
the available usage data are used as ground truth to train the convolutional
neural network. To create latent factor representations for the new items, the
convolutional neural network uses their textual description. The results from
the experiments reveal that the proposed approach significantly outperforms
several baseline estimators
A Probabilistic Model for the Cold-Start Problem in Rating Prediction using Click Data
One of the most efficient methods in collaborative filtering is matrix
factorization, which finds the latent vector representations of users and items
based on the ratings of users to items. However, a matrix factorization based
algorithm suffers from the cold-start problem: it cannot find latent vectors
for items to which previous ratings are not available. This paper utilizes
click data, which can be collected in abundance, to address the cold-start
problem. We propose a probabilistic item embedding model that learns item
representations from click data, and a model named EMB-MF, that connects it
with a probabilistic matrix factorization for rating prediction. The
experiments on three real-world datasets demonstrate that the proposed model is
not only effective in recommending items with no previous ratings, but also
outperforms competing methods, especially when the data is very sparse.Comment: ICONIP 201
An empirical comparison of collaborative filtering approaches on netflix data
Recommender systems are widely used in E-Commerce for making automatic suggestions of new items that could meet the interest of a given user. Collaborative Filtering approaches compute recommendations by assuming that users, who have shown similar behavior in the past, will share a common behavior in the future. According to this assumption, the most effective collaborative filtering techniques try to discover groups of similar users in order to infer the preferences of the group members. The purpose of this work is to show an empirical comparison of the main collaborative filtering approaches, namely Baseline, Nearest Neighbors, Latent Factor and Probabilistic models, focusing on their strengths and weaknesses. Data used for the analysis are a sample of the well-known Netix Prize database. Copyright owned by the authors
Implementasi dan Analisis Online – Updating Regularized Kernel Matrix Factorization Model pada Sistem Rekomendasi
Faktorisasi Matriks adalah salah satu metode yang digunakan pada Sistem Rekomendasi untuk membuat sebuah model prediksi rating. Salah satu jenisnya adalah Regularized Matriks Factorization yang mampu memberikan kualitas rekomendasi yang tinggi pada sebuah sistem rekomendasi. Akan tetapi, teknik - teknik Faktorisasi Matriks bermasalah jika model pada sistem rekomendasi berupa model yang statik. Permasalahan performansi terjadi, karena proses Learning data pada Faktorisasi Matriks membutuhkan waktu yang lama. Model Online dari Faktorisasi Matriks merupakan hal yang dapat memperbaiki model sebelumnya, dengan model Online, waktu yang dibutuhkan untuk melakukan proses prediksi untuk User dan Item yang baru, lebih cepat dibandingkan dengan model Offline faktorisasi matriks. Penelitian ini berfokus dalam menganalisis dan mengimplementasikan model Online dari Regularized Matriks Factorization pada sebuah sistem rekomendasi film. Hasil yang diperoleh adalah kualitas prediksi rating dengan metode Online Updating RKMF mengungguli kualitas prediksi rating dengan metode Full Retrain RKMF dengan perbedaan nilai RMSE sebesar 1.5% pada kondisi terburuk, dan dengan waktu prediksi yang sangat singkat.
Keyword : faktorisasi matriks, Online Updating, recommender performanc
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