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"Recommendation": models, code, and papers

From Zero-Shot Learning to Cold-Start Recommendation

Jun 21, 2019
Jingjing Li, Mengmeng Jing, Ke Lu, Lei Zhu, Yang Yang, Zi Huang

Zero-shot learning (ZSL) and cold-start recommendation (CSR) are two challenging problems in computer vision and recommender system, respectively. In general, they are independently investigated in different communities. This paper, however, reveals that ZSL and CSR are two extensions of the same intension. Both of them, for instance, attempt to predict unseen classes and involve two spaces, one for direct feature representation and the other for supplementary description. Yet there is no existing approach which addresses CSR from the ZSL perspective. This work, for the first time, formulates CSR as a ZSL problem, and a tailor-made ZSL method is proposed to handle CSR. Specifically, we propose a Low-rank Linear Auto-Encoder (LLAE), which challenges three cruxes, i.e., domain shift, spurious correlations and computing efficiency, in this paper. LLAE consists of two parts, a low-rank encoder maps user behavior into user attributes and a symmetric decoder reconstructs user behavior from user attributes. Extensive experiments on both ZSL and CSR tasks verify that the proposed method is a win-win formulation, i.e., not only can CSR be handled by ZSL models with a significant performance improvement compared with several conventional state-of-the-art methods, but the consideration of CSR can benefit ZSL as well.

* Accepted to AAAI 2019. Codes are available at 

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Micro-Behavior Encoding for Session-based Recommendation

Apr 05, 2022
Jiahao Yuan, Wendi Ji, Dell Zhang, Jinwei Pan, Xiaoling Wang

Session-based Recommendation (SR) aims to predict the next item for recommendation based on previously recorded sessions of user interaction. The majority of existing approaches to SR focus on modeling the transition patterns of items. In such models, the so-called micro-behaviors describing how the user locates an item and carries out various activities on it (e.g., click, add-to-cart, and read-comments), are simply ignored. A few recent studies have tried to incorporate the sequential patterns of micro-behaviors into SR models. However, those sequential models still cannot effectively capture all the inherent interdependencies between micro-behavior operations. In this work, we aim to investigate the effects of the micro-behavior information in SR systematically. Specifically, we identify two different patterns of micro-behaviors: "sequential patterns" and "dyadic relational patterns". To build a unified model of user micro-behaviors, we first devise a multigraph to aggregate the sequential patterns from different items via a graph neural network, and then utilize an extended self-attention network to exploit the pair-wise relational patterns of micro-behaviors. Extensive experiments on three public real-world datasets show the superiority of the proposed approach over the state-of-theart baselines and confirm the usefulness of these two different micro-behavior patterns for SR.

* Accepted by ICDE 2022 

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Providing reliability in Recommender Systems through Bernoulli Matrix Factorization

Jun 05, 2020
Fernando Ortega, Raúl Lara-Cabrera, Ángel González-Prieto, Jesús Bobadilla

Recommender Systems are giving increasing importance to the beyond accuracy quality measures, and reliability is one of the most important in the Collaborative Filtering context. This paper proposes Bernoulli Matrix Factorization (BeMF), a matrix factorization model to provide both prediction values and reliability ones. This is a very innovative approach from several perspectives: a) it acts on the model-based Collaborative Filtering, rather than in the memory-based one, b) it does not use external methods or extended architectures for providing reliability such as the existing solutions, c) it is based on a classification-based model, instead of the usual regression-based ones, and d) the matrix factorization formalism is supported by the Bernoulli distribution, to exploit the binary nature of the designed classification model. As expected, results show that the more reliable a prediction is, the less liable to be wrong: recommendation quality has been improved by selecting the most reliable predictions. State-of-the-Art quality measures for reliability have been tested, showing improved results compared to the baseline methods and models.

* 21 pages, 7 figures, 8 tables 

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Learning Cost-Effective and Interpretable Regimes for Treatment Recommendation

Nov 23, 2016
Himabindu Lakkaraju, Cynthia Rudin

Decision makers, such as doctors and judges, make crucial decisions such as recommending treatments to patients, and granting bails to defendants on a daily basis. Such decisions typically involve weighting the potential benefits of taking an action against the costs involved. In this work, we aim to automate this task of learning {cost-effective, interpretable and actionable treatment regimes. We formulate this as a problem of learning a decision list -- a sequence of if-then-else rules -- which maps characteristics of subjects (eg., diagnostic test results of patients) to treatments. We propose a novel objective to construct a decision list which maximizes outcomes for the population, and minimizes overall costs. We model the problem of learning such a list as a Markov Decision Process (MDP) and employ a variant of the Upper Confidence Bound for Trees (UCT) strategy which leverages customized checks for pruning the search space effectively. Experimental results on real world observational data capturing treatment recommendations for asthma patients demonstrate the effectiveness of our approach.

* Presented at NIPS 2016 Workshop on Interpretable Machine Learning in Complex Systems 

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Unreliable Multi-Armed Bandits: A Novel Approach to Recommendation Systems

Nov 14, 2019
Aditya Narayan Ravi, Pranav Poduval, Dr. Sharayu Moharir

We use a novel modification of Multi-Armed Bandits to create a new model for recommendation systems. We model the recommendation system as a bandit seeking to maximize reward by pulling on arms with unknown rewards. The catch however is that this bandit can only access these arms through an unreliable intermediate that has some level of autonomy while choosing its arms. For example, in a streaming website the user has a lot of autonomy while choosing content they want to watch. The streaming sites can use targeted advertising as a means to bias opinions of these users. Here the streaming site is the bandit aiming to maximize reward and the user is the unreliable intermediate. We model the intermediate as accessing states via a Markov chain. The bandit is allowed to perturb this Markov chain. We prove fundamental theorems for this setting after which we show a close-to-optimal Explore-Commit algorithm.

* 4 pages, 4 figures, Aditya Narayan Ravi and Pranav Poduval have equal contribution 

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Addressing Bias in Visualization Recommenders by Identifying Trends in Training Data: Improving VizML Through a Statistical Analysis of the Plotly Community Feed

Mar 09, 2022
Allen Tu, Priyanka Mehta, Alexander Wu, Nandhini Krishnan, Amar Mujumdar

Machine learning is a promising approach to visualization recommendation due to its high scalability and representational power. Researchers can create a neural network to predict visualizations from input data by training it over a corpus of datasets and visualization examples. However, these machine learning models can reflect trends in their training data that may negatively affect their performance. Our research project aims to address training bias in machine learning visualization recommendation systems by identifying trends in the training data through statistical analysis.

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Content-Based Top-N Recommendation using Heterogeneous Relations

Jun 27, 2016
Yifan Chen, Xiang Zhao, Junjiao Gan, Junkai Ren, Yang Fang

Top-$N$ recommender systems have been extensively studied. However, the sparsity of user-item activities has not been well resolved. While many hybrid systems were proposed to address the cold-start problem, the profile information has not been sufficiently leveraged. Furthermore, the heterogeneity of profiles between users and items intensifies the challenge. In this paper, we propose a content-based top-$N$ recommender system by learning the global term weights in profiles. To achieve this, we bring in PathSim, which could well measures the node similarity with heterogeneous relations (between users and items). Starting from the original TF-IDF value, the global term weights gradually converge, and eventually reflect both profile and activity information. To facilitate training, the derivative is reformulated into matrix form, which could easily be paralleled. We conduct extensive experiments, which demonstrate the superiority of the proposed method.

* 13 pages, 8 figures, ADC 2016 

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Modeling Sequences as Distributions with Uncertainty for Sequential Recommendation

Jun 11, 2021
Ziwei Fan, Zhiwei Liu, Lei Zheng, Shen Wang, Philip S. Yu

The sequential patterns within the user interactions are pivotal for representing the user's preference and capturing latent relationships among items. The recent advancements of sequence modeling by Transformers advocate the community to devise more effective encoders for the sequential recommendation. Most existing sequential methods assume users are deterministic. However, item-item transitions might fluctuate significantly in several item aspects and exhibit randomness of user interests. This \textit{stochastic characteristics} brings up a solid demand to include uncertainties in representing sequences and items. Additionally, modeling sequences and items with uncertainties expands users' and items' interaction spaces, thus further alleviating cold-start problems. In this work, we propose a Distribution-based Transformer for Sequential Recommendation (DT4SR), which injects uncertainties into sequential modeling. We use Elliptical Gaussian distributions to describe items and sequences with uncertainty. We describe the uncertainty in items and sequences as Elliptical Gaussian distribution. And we adopt Wasserstein distance to measure the similarity between distributions. We devise two novel Trans-formers for modeling mean and covariance, which guarantees the positive-definite property of distributions. The proposed method significantly outperforms the state-of-the-art methods. The experiments on three benchmark datasets also demonstrate its effectiveness in alleviating cold-start issues. The code is available in

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Sequential Recommendation with User Evolving Preference Decomposition

Mar 31, 2022
Weiqi Shao, Xu Chen, Long Xia, Jiashu Zhao, Dawei Yin

Modeling user sequential behaviors has recently attracted increasing attention in the recommendation domain. Existing methods mostly assume coherent preference in the same sequence. However, user personalities are volatile and easily changed, and there can be multiple mixed preferences underlying user behaviors. To solve this problem, in this paper, we propose a novel sequential recommender model via decomposing and modeling user independent preferences. To achieve this goal, we highlight three practical challenges considering the inconsistent, evolving and uneven nature of the user behavior, which are seldom noticed by the previous work. For overcoming these challenges in a unified framework, we introduce a reinforcement learning module to simulate the evolution of user preference. More specifically, the action aims to allocate each item into a sub-sequence or create a new one according to how the previous items are decomposed as well as the time interval between successive behaviors. The reward is associated with the final loss of the learning objective, aiming to generate sub-sequences which can better fit the training data. We conduct extensive experiments based on six real-world datasets across different domains. Compared with the state-of-the-art methods, empirical studies manifest that our model can on average improve the performance by about 8.21%, 10.08%, 10.32%, and 9.82% on the metrics of Precision, Recall, NDCG and MRR, respectively.

* sequential recommendation 

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