Deep Learning based Recommendation Systems

The usage of Internet applications, such as social networking and e-commerce is increasing exponentially, which leads to an increased offered content. Recommender systems help users filter out relevant content from a large pool of available content. The recommender systems play a vital role in today’s internet applications. Collaborative Filtering (CF) is one of the popular technique used to design recommendation systems. This technique recommends new content to users based on preferences that the user and similar users have. However, there are some shortcomings to current CF techniques, which affects negatively the performance of the recommendation models. In recent years, deep learning has achieved great success in natural language processing, computer vision and speech recognition. However, the use of deep learning in recommendation domain is relatively new. In this work, we tackle the shortcomings of collaborative filtering by using deep neural network techniques. Although some recent work has employed deep learning for recommendation, they only focused on modeling content descriptions, such as content information of items and auricular features of audios. Moreover, these models ignore the important factor of collaborative filtering, that is the user-item interaction function, but some models still employ matrix factorization, by using inner product on the latent features of items and users. In this project, the inner product is replaced by a neural network architecture, which learns an user-item interaction function from data. To handle any nonlinearities in the user-item interaction function, a multi-layer perceptron is used. Extensive experiments on two real-world datasets demonstrate improvements made by our model compared to existing popular collaborative filtering techniques. Empirical evidence shows deep learning based recommendation models have better performance

Influence of Social Circles on User Recommendations

Recommender systems are powerful tools that filter and recommend content relevant to a user. One of the most popular techniques used in recommender systems is collaborative filtering. Collaborative filtering has been successfully incorporated in many applications. However, these recommendation systems require a minimum number of users, items, and ratings in order to provide effective recommendations. This results in the infamous cold start problem where the system is not able to produce effective recommendations for new users. In recent times, with escalation in the popularity and usage of social networks, people tend to share their experiences in the form of reviews and ratings on social media. The components of social media like influence of friends, users\u27 interests, and friends\u27 interests create many opportunities to develop solutions for sparsity and cold start problems in recommender systems. This research observes these patterns and analyzes the role of social trust in baseline social recommender algorithms SocialMF - a matrix factorization-based model, SocialFD - a model that uses distance metric learning, and GraphRec - an attention-based deep learning model. Through extensive experimentation, this research compares the performance and results of these algorithms on datasets that these algorithms were tested on and one new dataset using the evaluations metrics such as root mean squared error (RMSE) and mean absolute error (MAE). By modifying the social trust component of these datasets, this project focuses on investigating the impact of trust on performance of these models. Experimental results of this research suggest that there is no conclusive evidence on how trust propagation plays a major part in these models. Moreover, these models show slightly improved performance when supplied with modified trust data

A Survey and Taxonomy of Sequential Recommender Systems for E-commerce Product Recommendation

E-commerce recommendation systems facilitate customers’ purchase decision by recommending products or services of interest (e.g., Amazon). Designing a recommender system tailored toward an individual customer’s need is crucial for retailers to increase revenue and retain customers’ loyalty. As users’ interests and preferences change with time, the time stamp of a user interaction (click, view or purchase event) is an important characteristic to learn sequential patterns from these user interactions and, hence, understand users’ long- and short-term preferences to predict the next item(s) for recommendation. This paper presents a taxonomy of sequential recommendation systems (SRecSys) with a focus on e-commerce product recommendation as an application and classifies SRecSys under three main categories as: (i) traditional approaches (sequence similarity, frequent pattern mining and sequential pattern mining), (ii) factorization and latent representation (matrix factorization and Markov models) and (iii) neural network-based approaches (deep neural networks, advanced models). This classification contributes towards enhancing the understanding of existing SRecSys in the literature with the application domain of e-commerce product recommendation and provides current status of the solutions available alongwith future research directions. Furthermore, a classification of surveyed systems according to eight important key features supported by the techniques along with their limitations is also presented. A comparative performance analysis of the presented SRecSys based on experiments performed on e-commerce data sets (Amazon and Online Retail) showed that integrating sequential purchase patterns into the recommendation process and modeling users’ sequential behavior improves the quality of recommendations

PERSONALIZED POINT OF INTEREST RECOMMENDATIONS WITH PRIVACY-PRESERVING TECHNIQUES

Location-based services (LBS) have become increasingly popular, with millions of people using mobile devices to access information about nearby points of interest (POIs). Personalized POI recommender systems have been developed to assist users in discovering and navigating these POIs. However, these systems typically require large amounts of user data, including location history and preferences, to provide personalized recommendations. The collection and use of such data can pose significant privacy concerns. This dissertation proposes a privacy-preserving approach to POI recommendations that address these privacy concerns. The proposed approach uses clustering, tabular generative adversarial networks, and differential privacy to generate synthetic user data, allowing for personalized recommendations without revealing individual user data. Specifically, the approach clusters users based on their fuzzy locations, generates synthetic user data using a tabular generative adversarial network and perturbs user data with differential privacy before it is used for recommendation. The proposed approaches achieve well-balanced trade-offs between accuracy and privacy preservation and can be applied to different recommender systems. The approach is evaluated through extensive experiments on real-world POI datasets, demonstrating that it is effective in providing personalized recommendations while preserving user privacy. The results show that the proposed approach achieves comparable accuracy to traditional POI recommender systems that do not consider privacy while providing significant privacy guarantees for users. The research\u27s contribution is twofold: it compares different methods for synthesizing user data specifically for POI recommender systems and offers a general privacy-preserving framework for different recommender systems. The proposed approach provides a novel solution to the privacy concerns of POI recommender systems, contributes to the development of more trustworthy and user-friendly LBS applications, and can enhance the trust of users in these systems

Software library for stream-based recommender systems

Tradicionalmente, um algoritmo de machine learning é capaz de aprender com dados, dado um conjunto tratado e construído anteriormente. Também é possível analisar esse conjunto de dados, usando técnicas de mineração de dados e extrair conclusões a partir dele. Ambos os conceitos têm inúmeras aplicações em todo o mundo, desde diagnósticos médicos até reconhecimento de fala ou mesmo consultas a mecanismos de pesquisa. No entanto, tradicionalmente, supõe-se que o conjunto de dados esteja disponível a todo o momento. Isso não é necessariamente verdade com os dados modernos pois os aplicativos de sistemas distribuídos recebem e processam milhões de fluxos de dados em uma fração de tempo limitado. Portanto, são necessárias técnicas para extrair e processar esses fluxos de dados, em um período de tempo limitado, com bons resultados e dimensionamento eficaz à medida que os dados aumentam. Um sistema específico de análise e previsão de conclusões futuras a partir de dados fornecidos são os sistemas de recomendação. Vários serviços online usam sistemas de recomendação para fornecer conteúdo personalizado a seus usuários. Em muitos casos, as recomendações são um dos geradores de tráfego mais eficazes nesses serviços. O problema reside em encontrar o melhor pequeno subconjunto de itens em um sistema que corresponda às preferências pessoais de cada usuário, através da análise de uma quantidade muito grande de dados históricos. Esse problema recebe mais atenção se for considerado um problema genérico, não específico, ou seja, se uma biblioteca for construída para que possa ser estendida e usada como uma ferramenta para ajudar a construir um sistema para um caso de uso específico. Podem-se distinguir soluções entre perfeitas ou estatisticamente semelhantes. Devido a grande quantidade de dados disponíveis, a decisão de reprocessar todos os dados, sempre que novos dados chegam, não seria viável; portanto, algoritmos incrementais são usados ​​para processar os dados recebidos e manter o modelo de recomendação atualizado. O objetivo real deste trabalho é implementar uma biblioteca que contenha e avalie essas abordagens incrementais para recomendações de que as atuais são específicas da tarefa.Traditionally, a machine learning algorithm is able to learn from data, given a previously built and treated data set. One can also analyze that data set, using data mining techniques, and draw conclusions from it. Both of these concepts have numerous world-wide applications, from medical diagnosis to speech recognition or even search engine queries. However, traditionally speaking, it is being assumed that the data set is available at all times. That is not necessarily true with modern data, as distributed systems applications receive and process millions of data streams on a limited time fraction. Therefore, there is a need for techniques to mine and process these data streams,on a limited time period with good results and effective scaling as data grows. One specific use case of analyzing and predicting future conclusions from given data, are recommendation systems.Several online services use recommender systems to deliver personalized content to their users.In many cases, recommendations are one of the most effective traffic generators in such services.The problem lies in finding the best small subset of items in a system that matches the personal preferences of each user, through the analysis of a very large amount of historical data. This problem gets more attention if it is considered as a generic problem, not as a specific one, that is,if a library is built so that it can be extended and used as a tool to help build a system for a specific use case. One can distinguish solutions between perfect ones or statistically similar ones. Due to the large amount of data available, the decision to reprocess all the data every time new data arrives, would not be feasible so, incremental algorithms are used to process incoming data and keeping the recommendation model updated. The real purpose of this work is to implement such a library which contains, and evaluates these incremental approaches to recommendation since current ones are task-specific

Constrained models for optimized recommender systems

For recommender systems based on matrix factorization techniques the recommendation step scales linearly with the number of objects in the catalog. This leads to a serious bottleneck in large-scale applications that have a strict time budget and in which there may be millions of items. In this work it is developed a probabilistic model for the recommender system that exploiting some constraints allows to give high quality suggestions in sublinear time

Consumer-side Fairness in Recommender Systems: A Systematic Survey of Methods and Evaluation

In the current landscape of ever-increasing levels of digitalization, we are facing major challenges pertaining to scalability. Recommender systems have become irreplaceable both for helping users navigate the increasing amounts of data and, conversely, aiding providers in marketing products to interested users. The growing awareness of discrimination in machine learning methods has recently motivated both academia and industry to research how fairness can be ensured in recommender systems. For recommender systems, such issues are well exemplified by occupation recommendation, where biases in historical data may lead to recommender systems relating one gender to lower wages or to the propagation of stereotypes. In particular, consumer-side fairness, which focuses on mitigating discrimination experienced by users of recommender systems, has seen a vast number of diverse approaches for addressing different types of discrimination. The nature of said discrimination depends on the setting and the applied fairness interpretation, of which there are many variations. This survey serves as a systematic overview and discussion of the current research on consumer-side fairness in recommender systems. To that end, a novel taxonomy based on high-level fairness interpretation is proposed and used to categorize the research and their proposed fairness evaluation metrics. Finally, we highlight some suggestions for the future direction of the field.Comment: Draft submitted to Springer (November 2022

A Network Science and Document Similarity based Hybrid Job Recommendation System

Tööde soovitussüsteemid kasutavad erinevaid andmeallikaid lõppkasutajale parema sisu tagamiseks. Hästi toimiva soovitussüsteemi arendamine nõuab keerulisi hübriidseid lähenemisi sarnasuse kujutamisele põhinedes töökuulutuste ja resümeede sisudele ja nendevahelistele interaktsioonidele. Antud töö tulemina arendati efektiivne võrgul baseeruv töökohtade soovitussüsteem, mis kasutab Personalized PageRank algoritmi töökohtade järjestamiseks põhinedes tööotsija resümee ja töökuulutuse kui tekstiliste dokumentide sarnasustele ning eelnevatele kasutaja ja töökuulutuste vahelistele interaktsioonidele.Meie lähenemine saavutas 50%-lise saagise ja tekitas online A/B testi jooksul rohkem kandideerimisi kui eelmised algoritmid.Job recommendation systems mainly use different sources of data in order to give the better content for the end user. Developing the well-performing system requires complex hybrid approaches of representing similarity based on the content of job postings and resumes as well as interactions between them. We develop an efficient hybrid network-based job recommendation system which uses Personalized PageRank algorithm in order to rank vacancies for the users based on the similarity between resumes and job posts as textual documents, along with previous interactions of users with vacancies. Our approach achieved the recall of 50% and generated more applies for the jobs during the online A/B test than previous algorithms

A probabilistic model for user interest propagation in recommender systems

User interests modeling has been exploited as a critical component to improve the predictive performance of recommender systems. However, with the absence of explicit information to model user interests, most approaches to recommender systems exploit users activities (user generated contents or user ratings) to inference the interest of users. In reality, the relationship among users also serves as a rich source of information of shared interest. To this end, we propose a framework which avoids the sole dependence of user activities to infer user interests and allows the exploitation of the direct relationship between users to propagate user interests to improve system's performance. In this paper, we advocate a novel modeling framework. We construct a probabilistic user interests model and propose a user interests propagation algorithm (UIP), which applies a factor graph based approach to estimate the distribution of the interests of users. Moreover, we incorporate our UIP algorithm with conventional matrix factorization (MF) for recommender systems. Experimental results demonstrate that our proposed approach outperforms previous methods used for recommender systems

Serialized Interacting Mixed Membership Stochastic Block Model

Last years have seen a regain of interest for the use of stochastic block modeling (SBM) in recommender systems. These models are seen as a flexible alternative to tensor decomposition techniques that are able to handle labeled data. Recent works proposed to tackle discrete recommendation problems via SBMs by considering larger contexts as input data and by adding second order interactions between contexts' related elements. In this work, we show that these models are all special cases of a single global framework: the Serialized Interacting Mixed membership Stochastic Block Model (SIMSBM). It allows to model an arbitrarily large context as well as an arbitrarily high order of interactions. We demonstrate that SIMSBM generalizes several recent SBM-based baselines. Besides, we demonstrate that our formulation allows for an increased predictive power on six real-world datasets.Comment: Published at ICDM 202