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Recsperts - Recommender Systems Experts

Marcel Kurovski

Recommender Systems are the most challenging, powerful and ubiquitous area of machine learning and artificial intelligence. This podcast hosts the experts in recommender systems research and application. From understanding what users really want to driving large-scale content discovery - from delivering personalized online experiences to catering to multi-stakeholder goals. Guests from industry and academia share how they tackle these and many more challenges. With Recsperts coming from universities all around the globe or from various industries like streaming, ecommerce, news, or social media, this podcast provides depth and insights. We go far beyond your 101 on RecSys and the shallowness of another matrix factorization based rating prediction blogpost! The motto is: be relevant or become irrelevant!
Expect a brand-new interview each month and follow Recsperts on your favorite podcast player.

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#34
September 1 · 1 hr 24 min
#33: Useful Recommender Systems and 20 Years of RecSys with Joseph Konstan
In episode 33 of Recsperts, I speak with Joseph A. Konstan, Distinguished McKnight University Professor and Distinguished University Teaching Professor at the University of Minnesota, co-founder of GroupLens, and the very first General Chair of the ACM RecSys conference back in 2007. This year he returns in that role as General Co-Chair of the 20th RecSys in Minneapolis. We talk about what actually makes a recommendation useful, why the field is more than a machine learning application, and how the community around RecSys came into being. We start with what Joe cares about most: usefulness. He recalls the supermarket thought experiment of printing "buy bananas and bread" on every shopping cart and explains why the early systems were valuable because they were wrong a lot. A recommender that took ten people like you and often got it wrong was also often surprising when it got it right, whereas today's systems are wrong far less and useless far more. As Joe puts it, "I don't care about prediction at all. I care about changing people's behavior." We discuss why optimizing for click-through in news reliably produces clickbait, why leave-one-out evaluation only makes sense if you assume the user already knew the right answer and had simply forgotten it, and why usefulness can never be read off a single metric but depends on the task, the context and the breadth of the user's intent. Sometimes the most useful thing is not the recommendation itself, but the stars, the reviews or the comparison table you put around it. From there we turn to the community itself. Joe traces it back to the spring of 1996 and the Berkeley Collaborative Filtering Workshop organized by Hal Varian and Paul Resnick, through a decade of scattered workshops at SIGIR, CSCW and CHI, to the first RecSys in 2007: a room on the Minnesota campus, over 120 people, and a substantial delegation from industry including Amazon. We discuss why the conference has always been heavily international and always at the intersection of research and practice, what surprised him most in 20 years (that we are still here and thriving), and the vision he pushed against the pull of becoming just another application of machine learning: a highly constrained, highly contextualized, multi-measure and often multi-stakeholder problem spanning algorithms, interfaces, data and business. This year the 20th RecSys comes home to Minneapolis, with Joe as General Co-Chair alongside George Karypis and Gediminas Adomavicius. We close on where things are heading. Joe's advice for newcomers is to immerse yourself in an application and find the real problems and opportunities there, rather than arriving enamored with a tool and treating every nail as something to hit. He picks up Karl Higley's point from the POPROX team that the research community keeps focusing on the model when the real object is the system: your algorithm is useless if it is not embedded in something that can deliver its results in a useful way. And he names the work he is most excited about — human decision-making and consumer psychology in the context of choice, the business school perspective that brings marketing and pricing into the picture, multi-sided marketplaces with their often invisible market maker, and the ethics of these systems as a practical lens on the long-term value our metrics still fail to capture. Enjoy this enriching episode of RECSPERTS – Recommender Systems Experts. Don’t forget to follow the podcast and please leave a review. (00:00) - Introduction (04:02) - About Joseph Konstan (10:57) - Loving and Hating Machine Learning (29:05) - What Makes Recommendations Useful (35:11) - Three Decades of GroupLens (40:29) - POPROX and Open Online Experimentation (51:41) - From the Berkeley Workshop to the First RecSys in 2007 (01:11:00) - 20 Years of RecSys and the Vision for the Field (01:17:38) - Further Challenges and Closing Remarks Links from the Episode: Joseph Konstan on LinkedIn Website of Joseph Konstan GroupLens Research POPROX: Platform for OPen Recommendation and Online eXperimentation Net Perceptions LensKit: Python Recommendation Toolkit Recommender Systems Specialization on Coursera (Konstan & Ekstrand) ACM TechTalk by Joseph Konstan: Recommender Systems - Beyond Machine Learning ACM TechTalk by Joseph Konstan: Recommender Systems - The Power of Personalization RecSys: The ACM Conference on Recommender Systems TLDR AI Newsletter Associated Press Papers: Resnick et al. (1994): GroupLens - An Open Architecture for Collaborative Filtering of Netnews Hill et al. (1995): Recommending and Evaluating Choices in a Virtual Community of Use Shardanand & Maes (1995): Social Information Filtering - Algorithms for Automating "Word of Mouth" Resnick & Varian (1997): Recommender Systems (CACM Special Issue) Sarwar et al. (2001): Item-Based Collaborative Filtering Recommendation Algorithms Das et al. (2007): Google News Personalization - Scalable Online Collaborative Filtering Su et al. (2023): Long-Term Value of Exploration - Measurements, Findings and Algorithms Tran et al. (2024): Transformers Meet ACT-R - Repeat-Aware and Sequential Listening Session Recommendation (Deezer) Ekstrand et al. (2024): Conducting Recommender Systems User Studies Using POPROX Higley et al. (2025): What News Recommendation Research Did (But Mostly Didn't) Teach Us About Building A News Recommender General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#33
May 12 · 1 hr 48 min
#32: RecSys in the Delivery Industry at Wolt with Sasha Fedintsev
In episode 32 of Recsperts, I’m joined by my colleague Sasha Fedintsev, Staff Applied Scientist at Wolt (DoorDash), working across personalization and ads, to unpack the realities of building large-scale recommender systems in food, grocery, and retail delivery. Together, we discuss the specifics of personalization in the delivery domain, and the models and ideas that power Wolt’s recommender system across 30+ markets - where theory quickly meets messy, high-stakes practice. We explore what makes this domain fundamentally different from traditional e-commerce: strong locality constraints, real-time context, and a heavy skew toward repurchasing behavior. Sasha explains how these factors break many textbook approaches - like standard collaborative filtering - and require creative adaptations such as clustering strategies and multi-stage ranking systems optimized for latency, all while respecting locality constraints. We also discuss the evolution of recommendation approaches over time - from classical collaborative filtering with ALS, to Neural Collaborative Filtering with BPR, and ultimately to transformer-based models for user sequence modeling and next-purchase prediction powering today’s venue ranking systems. We also touch on practical challenges such as evaluation in real-world systems, including A/B testing pitfalls and biases in logged data, as well as the complexity introduced by multi-surface experiences like discovery pages, vertical lists, and search. Beyond venues, we discuss why item-level recommendation is an order of magnitude harder - due to scale, context dependence, and availability constraints - and what this implies for future system design. Throughout the episode, Sasha provides a candid view on the evolving role of a Staff Applied Scientist - bridging research and production, setting scientific standards, and driving cross-team impact. Enjoy this enriching episode of RECSPERTS – Recommender Systems Experts. Don’t forget to follow the podcast and please leave a review. (00:00) - Introduction (05:10) - About Sasha Fedintsev (15:26) - The Role of a Staff Applied Scientist (25:50) - Challenges and Specifics of the Delivery Industry (47:24) - Ranking and Recommendation Problems at Wolt (51:31) - NCF with BPR for Wolt's First DNN Recommendation Model (01:16:43) - User Sequence Transformers for Next Purchase Prediction (01:26:51) - Explore vs. Exploit or New vs. Recurring Purchases (01:31:29) - Ads Personalization at Wolt (01:36:16) - Further Challenges in RecSys (01:37:58) - A Final Note on Radical Longevity (01:46:30) - Closing Remarks Links from the Episode: Alexander "Sasha" Fedintsev on LinkedIn Alexander on X Wolt Alexander Fedintsev at Wolt Tech Talks: Restaurant discovery with Wolt: Deep Neural Networks to power recommendations H3 Geospatial Indexing System Recommenders Repository Tanja Reilly: The Staff Engineer's Path Will Larson: Staff Engineer: Leadership beyond the management track Coupon collector's problem Alexander Fedintsev (2026): Longevity Bottlenecks: Part I — Dementia Papers: Rendle et al. (2009): BPR: Bayesian personalized ranking from implicit feedback He et al. (2017): Neural Collaborative Filtering Dacrema et al. (2019): Are we really making much progress? A worrying analysis of recent neural recommendation approaches Rendle et al (2020): Neural Collaborative Filtering vs. Matrix Factorization Revisited Hu et al. (2008): Collaborative Filtering for Implicit Feedback Datasets Grbovic et al. (2015): E-commerce in Your Inbox: Product Recommendations at Scale Quadrana et al. (2018): Sequence-Aware Recommender Systems Su et al. (2024): Long-Term Value of Exploration: Measurements, Findings and Algorithms Tran et al. (2024): Transformers Meet ACT-R: Repeat-Aware and Sequential Listening Session Recommendation Lichtenberg et al. (2024): Ranking Across Different Content Types: The Robust Beauty of Multinomial Blending General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#32
February 19 · 1 hr 37 min
#31: Psychology-Aware Recommender Systems with Elisabeth Lex
In episode 31 of Recsperts, I sit down with Elisabeth Lex, Full Professor of Human-Computer Interfaces and Inclusive Technologies at Graz University of Technology and a leading researcher at the intersection of recommender systems, psychology, and human–computer interaction. Together, we explore how recommender systems can become truly human-centric by integrating cognitive, emotional, and personality-aware models into their design. Elisabeth begins by addressing a common reductionism in the field: treating users primarily as data points rather than as humans with goals, emotions, memories, and cognitive boundaries. We revisit the origins of psychology-informed recommendation, including the Grundy system -the first recommender system, built nearly 50 years ago - which framed book recommendation through stereotype modeling. From there, we discuss how the community’s focus shifted toward solving recommendation mainly as an algorithmic optimization problem, often sidelining richer models of human decision-making. We then map out the three major branches of psychology-informed RecSys - cognition-inspired, affect-aware, and personality-aware - and dive into practical examples. Elisabeth walks us through her work on modeling music re-listening behavior using cognitive architectures such as ACT-R (Adaptive Control of Thought–Rational) and shows how cognitive constructs like memory decay, attention, and familiarity can meaningfully augment standard approaches like collaborative filtering. We also explore how hybrid systems that combine cognitive models with collaborative filtering can yield not just higher accuracy but also more novelty, diversity, and clearer explanations. Our conversation also turns to user-centric evaluation. Elisabeth argues that accuracy metrics alone cannot tell us whether a system is genuinely helpful. Instead, we must measure attitudes, perceptions, motivations, and emotional responses - while carefully accounting for cognitive biases, UI effects, and users’ lived experiences. Towards the end, Elisabeth discusses emerging research directions such as hybrid AI (symbolic + sub-symbolic methods), the role of LLMs and agents, the risks of replacing human studies with automated evaluations, and the responsibility our community has to understand users beyond their clicks. Enjoy this enriching episode of RECSPERTS – Recommender Systems Experts. Don’t forget to follow the podcast and please leave a review. (00:00) - Introduction (03:15) - About Elisabeth Lex (07:55) - Grundy, the first Recommender System (09:03) - Bridging the Gap between Psychology and Modern RecSys (17:21) - On how and when Elisabeth became a Researcher (21:39) - Survey on Psychology-Informed RecSys (39:29) - Personality-Aware Recommendation (49:43) - Affect- and Emotion-Aware Recommendation (01:01:37) - Cognition-Inspired Recommendation and the ACT-R Framework (01:14:39) - Combining Collaborative Filtering and ACT-R for Explainability (01:21:26) - Human-Centered Design (01:26:15) - Further Challenges and Closing Remarks Links from the Episode: Elisabeth Lex on LinkedIn Website of Elisabeth AI for Society Lab First International Workshop on Recommender Systems for Sustainability and Social Good | co-located with RecSys 2024 Second International Workshop on Recommender Systems for Sustainability and Social Good | co-located with RecSys 2025 HyPer Workshop: Hybrid AI for Human-Centric Personalization Tutorial on Psychology-Informed RecSys ACT-R: Adaptive Control of Thought-Rational POPROX: Platform for OPen Recommendation and Online eXperimentation Papers: Elaine Rich (1979): User Modeling via Stereotypes Lex et al. (2021): Psychology-informed Recommender Systems Reiter-Haas et al. (2021): Predicting Music Relistening Behavior Using the ACT-R Framework Moscati et al. (2023): Integrating the ACT-R Framework with Collaborative Filtering for Explainable Sequential Music Recommendation Tran et al. (2024): Transformers Meet ACT-R: Repeat-Aware and Sequential Listening Session Recommendation General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#31
January 28 · 1 hr 32 min
#30: Serendipity for Recommender Systems with Annelien Smets
In episode 30 of Recsperts, I speak with Annelien Smets, Professor at Vrije Universiteit Brussel and Senior Researcher at imec-SMIT, about the value, perception, and practical design of serendipity in recommender systems. Annelien introduces her framework for understanding serendipity through intention, experience, and affordances, and explains the paradox of artificial serendipity - why it cannot be engineered, but only designed for. We start by unpacking the paradox of serendipity: while serendipity cannot be engineered or planned, systems and environments can be designed to increase the likelihood that serendipitous experiences occur. Annelien explains why randomness alone is not enough and why serendipity always emerges from an interplay between an unexpected encounter and a user’s ability to recognize its relevance and value. A central part of our discussion focuses on Annelien’s recent framework that distinguishes between intended, experienced, and afforded serendipity. We explore why organizations first need to clarify why they want serendipity - whether as an ideal, a common good, a mediator to achieve other goals (such as long-term retention or long-tail exposure), or even as a product feature in itself. From there, we dive into how users actually experience serendipity, drawing on qualitative interview research that identifies three core components: encounters must feel fortuitous, refreshing, and enriching. These components can manifest in different “flavors,” such as taste broadening, taste deepening, or rediscovering forgotten interests. We then move beyond algorithms to discuss affordances for serendipity - design principles that span content, user interfaces, and information access. Using examples from libraries, urban spaces, and digital platforms, Annelien shows why serendipity is a system-level property rather than a single metric or model tweak. We also discuss where serendipity can go wrong, including the Netflix “Surprise Me” feature, and why mismatched expectations can actually harm user experience. To close, we reflect on open research questions, from measuring different types of serendipity to understanding how content types, business models, and platform economics shape what is possible. Annelien also challenges a common myth: serendipity does not automatically burst filter bubbles—and should not be treated as a silver bullet. Enjoy this enriching episode of RECSPERTS – Recommender Systems Experts. Don’t forget to follow the podcast and please leave a review. (00:00) - Introduction (03:57) - About Annelien Smets (14:42) - Paradox and Definition of (Artificial) Serendipity (27:04) - Intended Serendipity (43:01) - Experienced Serendipity (01:01:18) - Afforded Serendipity (01:13:49) - Examples of Serendipity Going Wrong (01:17:40) - Framework for Serendipity (01:22:41) - Further Challenges and Closing Remarks Links from the Episode: Annelien Smets on LinkedIn Website of Annelien LinkedIn Article by Annelien Smets (2025): Overcoming the Paradox of Artificial Serendipity The Serendipity Society Serendipity Engine Papers: Smets (2025): Intended, afforded, and experienced serendipity: overcoming the paradox of artificial serendipity Smets et al. (2022): Serendipity in Recommender Systems Beyond the Algorithm: A Feature Repository and Experimental Design Binst et al. (2025): What Is Serendipity? An Interview Study to Conceptualize Experienced Serendipity in Recommender Systems Ziarani et al. (2021): Serendipity in Recommender Systems: A Systematic Literature Review Chen et al. (2021): Values of User Exploration in Recommender Systems Smets et al. (2025): Why Do Recommenders Recommend? Three Waves of Research Perspectives on Recommender Systems Smets (2023): Designing for Serendipity, a Means or an End? General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#30
Aug 27, 2025 · 1 hr 37 min
#29: Transformers for Recommender Systems with Craig Macdonald and Sasha Petrov
In episode 29 of Recsperts, I welcome Craig Macdonald, Professor of Information Retrieval at the University of Glasgow, and Aleksandr “Sasha” Petrov, PhD researcher and former applied scientist at Amazon. Together, we dive deep into sequential recommender systems and the growing role of transformer models such as SASRec and BERT4Rec. Our conversation begins with their influential replicability study of BERT4Rec, which revealed inconsistencies in reported results and highlighted the importance of training objectives over architecture tweaks. From there, Craig and Sasha guide us through their award-winning research on making transformers for sequential recommendation with large corpora both more effective and more efficient. We discuss how recency sampling (RSS) reduces training times dramatically, and how gSASRec overcomes the problem of overconfidence in models trained with negative sampling. By generalizing the sigmoid function (gBCE), they were able to reconcile cross-entropy–based optimization results with negative sampling, matching the effectiveness of softmax approaches while keeping training scalable for large corpora. We also explore RecJPQ, their recent work on joint product quantization for item embeddings. This approach makes transformer-based sequential recommenders substantially faster at inference and far more memory-efficient for embeddings—while sometimes even improving effectiveness thanks to regularization effects. Towards the end, Craig and Sasha share their perspective on generative approaches like GPTRec, the promises and limits of large language models in recommendation, and what challenges remain for the future of sequential recommender systems. Enjoy this enriching episode of RECSPERTS – Recommender Systems Experts. Don’t forget to follow the podcast and please leave a review. (00:00) - Introduction (04:09) - About Craig Macdonald (04:46) - About Sasha Petrov (13:48) - Tutorial on Transformers for Sequential Recommendations (19:24) - SASRec vs. BERT4Rec (21:25) - Replicability Study of BERT4Rec for Sequential Recommendation (32:52) - Training Sequential RecSys using Recency Sampling (40:01) - gSASRec for Reducing Overconfidence by Negative Sampling (01:00:51) - RecJPQ: Training Large-Catalogue Sequential Recommenders (01:21:37) - Generative Sequential Recommendation with GPTRec (01:29:12) - Further Challenges and Closing Remarks Links from the Episode: Craig Macdonald on LinkedIn Sasha Petrov on LinkedIn Sasha's Website Tutorial: Transformers for Sequential Recommendation (ECIR 2024) Tutorial Recording from ACM European Summer School in Bari (2024) Talk: Neural Recommender Systems (European Summer School in Information Retrieval 2024) Papers: Kang et al. (2018): Self-Attentive Sequential Recommendation Sun et al. (2019): BERT4Rec: Sequential Recommendation with Bidirectional Encoder Representations from Transformer Petrov et al. (2022): A Systematic Review and Replicability Study of BERT4Rec for Sequential Recommendation Petrov et al. (2022): Effective and Efficient Training for Sequential Recommendation using Recency Sampling Petrov et al. (2024): RSS: Effective and Efficient Training for Sequential Recommendation Using Recency Sampling (extended version) Petrov et al. (2023): gSASRec: Reducing Overconfidence in Sequential Recommendation Trained with Negative Sampling Petrov et al. (2025): Improving Effectiveness by Reducing Overconfidence in Large Catalogue Sequential Recommendation with gBCE loss Petrov et al. (2024): RecJPQ: Training Large-Catalogue Sequential Recommenders Petrov et al. (2024): Efficient Inference of Sub-Item Id-based Sequential Recommendation Models with Millions of Items Rajput et al. (2023): Recommender Systems with Generative Retrieval Petrov et al. (2023): Generative Sequential Recommendation with GPTRec Petrov et al. (2024): Aligning GPTRec with Beyond-Accuracy Goals with Reinforcement Learning General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website Disclaimer: Craig holds concurrent appointments as a Professor of Information Retrieval at University of Glasgow and as an Amazon Scholar. This podcast describes work performed at the University of Glasgow and is not associated with Amazon.
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#29
Apr 15, 2025 · 1 hr 35 min
#28: Multistakeholder Recommender Systems with Robin Burke
In episode 28 of Recsperts, I sit down with Robin Burke, professor of information science at the University of Colorado Boulder and a leading expert with over 30 years of experience in recommender systems. Together, we explore multistakeholder recommender systems, fairness, transparency, and the role of recommender systems in the age of evolving generative AI. We begin by tracing the origins of recommender systems, traditionally built around user-centric models. However, Robin challenges this perspective, arguing that all recommender systems are inherently multistakeholder—serving not just consumers as the recipients of recommendations, but also content providers, platform operators, and other key players with partially competing interests. He explains why the common “Recommended for You” label is, at best, an oversimplification and how greater transparency is needed to show how stakeholder interests are balanced. Our conversation also delves into practical approaches for handling multiple objectives, including reranking strategies versus integrated optimization. While embedding multistakeholder concerns directly into models may be ideal, reranking offers a more flexible and efficient alternative, reducing the need for frequent retraining. Towards the end of our discussion, we explore post-userism and the impact of generative AI on recommendation systems. With AI-generated content on the rise, Robin raises a critical concern: if recommendation systems remain overly user-centric, generative content could marginalize human creators, diminishing their revenue streams. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (03:24) - About Robin Burke and First Recommender Systems (26:07) - From Fairness and Advertising to Multistakeholder RecSys (34:10) - Multistakeholder RecSys Terminology (40:16) - Multistakeholder vs. Multiobjective (42:43) - Reciprocal and Value-Aware RecSys (59:14) - Objective Integration vs. Reranking (01:06:31) - Social Choice for Recommendations under Fairness (01:17:40) - Post-Userist Recommender Systems (01:26:34) - Further Challenges and Closing Remarks Links from the Episode: Robin Burke on LinkedIn Robin's Website That Recommender Systems Lab Reference to Broder's Keynote on Computational Advertising and Recommender Systems from RecSys 2008 Multistakeholder Recommender Systems (from Recommender Systems Handbook), chapter by Himan Abdollahpouri & Robin Burke POPROX: The Platform for OPen Recommendation and Online eXperimentation AltRecSys 2024 (Workshop at RecSys 2024) Papers: Burke et al. (1996): Knowledge-Based Navigation of Complex Information Spaces Burke (2002): Hybrid Recommender Systems: Survey and Experiments Resnick et al. (1997): Recommender Systems Goldberg et al. (1992): Using collaborative filtering to weave an information tapestry Linden et al. (2003): Amazon.com Recommendations - Item-to-Item Collaborative Filtering Aird et al. (2024): Social Choice for Heterogeneous Fairness in Recommendation Aird et al. (2024): Dynamic Fairness-aware Recommendation Through Multi-agent Social Choice Burke et al. (2024): Post-Userist Recommender Systems : A Manifesto Baumer et al. (2017): Post-userism Burke et al. (2024): Conducting Recommender Systems User Studies Using POPROX General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#28
Mar 19, 2025 · 1 hr 27 min
#27: Recommender Systems at the BBC with Alessandro Piscopo and Duncan Walker
In episode 27 of Recsperts, we meet Alessandro Piscopo, Lead Data Scientist in Personalization and Search, and Duncan Walker, Principal Data Scientist in the iPlayer Recommendations Team, both from the BBC. We discuss how the BBC personalizes recommendations across different offerings like news or video and audio content recommendations. We learn about the core values for the oldest public service media organization and the collaboration with editors in that process. The BBC once started with short video recommendations for BBC+ and nowadays has to consider recommendations across multiple domains: news, the iPlayer, BBC Sounds, BBC Bytesize, and more. With a reach of about 500M+ users who access services every week there is a huge potential. My guests discuss the challenges of aligning recommendations with public service values and the role of editors and constant exchange, alignment, and learning between the algorithmic and editorial lines of recommender systems. We also discuss the potential of cross-domain recommendations to leverage the content across different products as well as the organizational setup of teams working on recommender systems at the BBC. We learn about skews in the data due to the nature of an online service that also has a linear offering with TV and radio services. Towards the end, we also touch a bit on QUARE @ RecSys, which is the Workshop on Measuring the Quality of Explanations in Recommender Systems. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (03:10) - About Alessandro Piscopo and Duncan Walker (14:53) - RecSys Applications at the BBC (20:22) - Journey of Building Public Service Recommendations (28:02) - Role and Implementation of Public Service Values (36:52) - Algorithmic and Editorial Recommendation (01:01:54) - Further RecSys Challenges at the BBC (01:15:53) - Quare Workshop (01:23:27) - Closing Remarks Links from the Episode: Alessandro Piscopo on LinkedIn Duncan Walker on LinkedIn BBC QUARE @ RecSys 2023 (2nd Workshop on Measuring the Quality of Explanations in Recommender Systems) Papers: Clarke et al. (2023): Personalised Recommendations for the BBC iPlayer: Initial approach and current challenges Boididou et al. (2021): Building Public Service Recommenders: Logbook of a Journey Piscopo et al. (2019): Data-Driven Recommendations in a Public Service Organisation General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#27
Feb 19, 2025 · 1 hr 35 min
#26: Diversity in Recommender Systems with Sanne Vrijenhoek
In episode 26 of Recsperts, I speak with Sanne Vrijenhoek, a PhD candidate at the University of Amsterdam’s Institute for Information Law and the AI, Media & Democracy Lab. Sanne’s research explores diversity in recommender systems, particularly in the news domain, and its connection to democratic values and goals. We dive into four of her papers, which focus on how diversity is conceptualized in news recommender systems. Sanne introduces us to five rank-aware divergence metrics for measuring normative diversity and explains why diversity evaluation shouldn’t be approached blindly—first, we need to clarify the underlying values. She also presents a normative framework for these metrics, linking them to different democratic theory perspectives. Beyond evaluation, we discuss how to optimize diversity in recommender systems and reflect on missed opportunities—such as the RecSys Challenge 2024, which could have gone beyond accuracy-chasing. Sanne also shares her recommendations for improving the challenge by incorporating objectives such as diversity. During our conversation, Sanne shares insights on effectively communicating recommender systems research to non-technical audiences. To wrap up, we explore ideas for fostering a more diverse RecSys research community, integrating perspectives from multiple disciplines. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (03:24) - About Sanne Vrijenhoek (14:49) - What Does Diversity in RecSys Mean? (26:32) - Assessing Diversity in News Recommendations (34:54) - Rank-Aware Divergence Metrics to Measure Normative Diversity (01:01:37) - RecSys Challenge 2024 - Recommendations for the Recommenders (01:11:23) - RecSys Workshops - NORMalize and AltRecSys (01:15:39) - On the Different Conceptualizations of Diversity in RecSys (01:28:38) - Closing Remarks Links from the Episode: Sanne Vrijenhoek on LinkedIn Informfully MIND: MIcrosoft News Dataset RecSys Challenge 2024 NORMalize 2023: The First Workshop on the Normative Design and Evaluation of Recommender Systems NORMalize 2024: The Second Workshop on the Normative Design and Evaluation of Recommender Systems AltRecSys 2024: The AltRecSys Workshop on Alternative, Unexpected, and Critical Ideas in Recommendation Papers: Vrijenhoek et al. (2021): Recommenders with a Mission: Assessing Diversity in News Recommendations Vrijenhoek et al. (2022): RADio – Rank-Aware Divergence Metrics to Measure Normative Diversity in News Recommendations Heitz et al. (2024): Recommendations for the Recommenders: Reflections on Prioritizing Diversity in the RecSys Challenge Vrijenhoek et al. (2024): Diversity of What? On the Different Conceptualizations of Diversity in Recommender Systems Helberger (2019): On the Democratic Role of News Recommenders Steck (2018): Calibrated Recommendations General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#26
Oct 12, 2024 · 39 min
#25: RecSys 2024 Special
In episode 25, we talk about the upcoming ACM Conference on Recommender Systems 2024 (RecSys) and welcome a former guest to geek about the conference. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (01:56) - Overview RecSys 2024 (07:01) - Contribution Stats (09:37) - Interview Links from the Episode: RecSys 2024 Conference Website Papers: RecSys '24: Proceedings of the 18th ACM Conference on Recommender Systems General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#25
Oct 1, 2024 · 1 hr 21 min
#24: Video Recommendations at Facebook with Amey Dharwadker
In episode 24 of Recsperts, I sit down with Amey Dharwadker, Machine Learning Engineering Manager at Facebook, to dive into the complexities of large-scale video recommendations. Amey, who leads the Video Recommendations Quality Ranking team at Facebook, sheds light on the intricate challenges of delivering personalized video feeds at scale. Our conversation covers content understanding, user interaction data, real-time signals, exploration, and evaluation techniques. We kick off the episode by reflecting on the inaugural VideoRecSys workshop at RecSys 2023, setting the stage for a deeper discussion on Facebook’s approach to video recommendations. Amey walks us through the critical challenges they face, such as gathering reliable user feedback signals to avoid pitfalls like watchbait. With a vast and ever-growing corpus of billions of videos—millions of which are added each month—the cold start problem looms large. We explore how content understanding, user feedback aggregation, and exploration techniques help address this issue. Amey explains how engagement metrics like watch time, comments, and reactions are used to rank content, ensuring users receive meaningful and diverse video feeds. A key highlight of the conversation is the importance of real-time personalization in fast-paced environments, such as short-form video platforms, where user preferences change quickly. Amey also emphasizes the value of cross-domain data in enriching user profiles and improving recommendations. Towards the end, Amey shares his insights on leadership in machine learning teams, pointing out the characteristics of a great ML team. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (02:32) - About Amey Dharwadker (08:39) - Video Recommendation Use Cases on Facebook (16:18) - Recommendation Teams and Collaboration (25:04) - Challenges of Video Recommendations (31:07) - Video Content Understanding and Metadata (33:18) - Multi-Stage RecSys and Models (42:42) - Goals and Objectives (49:04) - User Behavior Signals (59:38) - Evaluation (01:06:33) - Cross-Domain User Representation (01:08:49) - Leadership and What Makes a Great Recommendation Team (01:13:01) - Closing Remarks Links from the Episode: Amey Dharwadker on LinkedIn Amey's Website RecSys Challenge 2021 VideoRecSys Workshop 2023 VideoRecSys + LargeRecSys 2024 Papers: Mahajan et al. (2023): CAViaR: Context Aware Video Recommendations Mahajan et al. (2023): PIE: Personalized Interest Exploration for Large-Scale Recommender Systems Raul et al. (2023): CAM2: Conformity-Aware Multi-Task Ranking Model for Large-Scale Recommender Systems Zhai et al. (2024): Actions Speak Louder than Words: Trillion-Parameter Sequential Transducers for Generative Recommendations Saket et al. (2023): Formulating Video Watch Success Signals for Recommendations on Short Video Platforms Wang et al. (2022): Surrogate for Long-Term User Experience in Recommender Systems Su et al. (2024): Long-Term Value of Exploration: Measurements, Findings and Algorithms General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#24
Aug 16, 2024 · 1 hr 54 min
#23: Generative Models for Recommender Systems with Yashar Deldjoo
In episode 23 of Recsperts, we welcome Yashar Deldjoo, Assistant Professor at the Polytechnic University of Bari, Italy. Yashar's research on recommender systems includes multimodal approaches, multimedia recommender systems as well as trustworthiness and adversarial robustness, where he has published a lot of work. We discuss the evolution of generative models for recommender systems, modeling paradigms, scenarios as well as their evaluation, risks and harms. We begin our interview with a reflection of Yashar's areas of recommender systems research so far. Starting with multimedia recsys, particularly video recommendations, Yashar covers his work around adversarial robustness and trustworthiness leading to the main topic for this episode: generative models for recommender systems. We learn about their aspects for improving beyond the (partially saturated) state of traditional recommender systems: improve effectiveness and efficiency for top-n recommendations, introduce interactivity beyond classical conversational recsys, provide personalized zero- or few-shot recommendations. We learn about the modeling paradigms and as well about the scenarios for generative models which mainly differ by input and modelling approach: ID-based, text-based, and multimodal generative models. This is how we navigate the large field of acronyms leading us from VAEs and GANs to LLMs. Towards the end of the episode, we also touch on the evaluation, opportunities, risks and harms of generative models for recommender systems. Yashar also provides us with an ample amount of references and upcoming events where people get the chance to know more about GenRecSys. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (03:58) - About Yashar Deldjoo (09:34) - Motivation for RecSys (13:05) - Intro to Generative Models for Recommender Systems (44:27) - Modeling Paradigms for Generative Models (51:33) - Scenario 1: Interaction-Driven Recommendation (57:59) - Scenario 2: Text-based Recommendation (01:10:39) - Scenario 3: Multimodal Recommendation (01:24:59) - Evaluation of Impact and Harm (01:38:07) - Further Research Challenges (01:45:03) - References and Research Advice (01:49:39) - Closing Remarks Links from the Episode: Yashar Deldjoo on LinkedIn Yashar's Website KDD 2024 Tutorial: Modern Recommender Systems Leveraging Generative AI: Fundamentals, Challenges and Opportunities RecSys 2024 Workshop: The 1st Workshop on Risks, Opportunities, and Evaluation of Generative Models in Recommender Systems (ROEGEN@RECSYS'24) Papers: Deldjoo et al. (2024): A Review of Modern Recommender Systems Using Generative Models (Gen-RecSys) Deldjoo et al. (2020): Recommender Systems Leveraging Multimedia Content Deldjoo et al. (2021): A Survey on Adversarial Recommender Systems: From Attack/Defense Strategies to Generative Adversarial Networks Deldjoo et al. (2020): How Dataset Characteristics Affect the Robustness of Collaborative Recommendation Models Liang et al. (2018): Variational Autoencoders for Collaborative Filtering He et al. (2016): Visual Bayesian Personalized Ranking from Implicit Feedback General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#23
Jun 6, 2024 · 1 hr 24 min
#22: Pinterest Homefeed and Ads Ranking with Prabhat Agarwal and Aayush Mudgal
In episode 22 of Recsperts, we welcome Prabhat Agarwal, Senior ML Engineer, and Aayush Mudgal, Staff ML Engineer, both from Pinterest, to the show. Prabhat works on recommendations and search systems at Pinterest, leading representation learning efforts. Aayush is responsible for ads ranking and privacy-aware conversion modeling. We discuss user and content modeling, short- vs. long-term objectives, evaluation as well as multi-task learning and touch on counterfactual evaluation as well. In our interview, Prabhat guides us through the journey of continuous improvements of Pinterest's Homefeed personalization starting with techniques such as gradient boosting over two-tower models to DCN and transformers. We discuss how to capture users' short- and long-term preferences through multiple embeddings and the role of candidate generators for content diversification. Prabhat shares some details about position debiasing and the challenges to facilitate exploration. With Aayush we get the chance to dive into the specifics of ads ranking at Pinterest and he helps us to better understand how multifaceted ads can be. We learn more about the pain of having too many models and the Pinterest's efforts to consolidate the model landscape to improve infrastructural costs, maintainability, and efficiency. Aayush also shares some insights about exploration and corresponding randomization in the context of ads and how user behavior is very different between different kinds of ads. Both guests highlight the role of counterfactual evaluation and its impact for faster experimentation. Towards the end of the episode, we also touch a bit on learnings from last year's RecSys challenge. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (03:51) - Guest Introductions (09:57) - Pinterest Introduction (21:57) - Homefeed Personalization (47:27) - Ads Ranking (01:14:58) - RecSys Challenge 2023 (01:20:26) - Closing Remarks Links from the Episode: Prabhat Agarwal on LinkedIn Aayush Mudgal on LinkedIn RecSys Challenge 2023 Pinterest Engineering Blog Pinterest Labs Prabhat's Talk at GTC 2022: Evolution of web-scale engagement modeling at Pinterest Blogpost: How we use AutoML, Multi-task learning and Multi-tower models for Pinterest Ads Blogpost: Pinterest Home Feed Unified Lightweight Scoring: A Two-tower Approach Blogpost: Experiment without the wait: Speeding up the iteration cycle with Offline Replay Experimentation Blogpost: MLEnv: Standardizing ML at Pinterest Under One ML Engine to Accelerate Innovation Blogpost: Handling Online-Offline Discrepancy in Pinterest Ads Ranking System Papers: Eksombatchai et al. (2018): Pixie: A System for Recommending 3+ Billion Items to 200+ Million Users in Real-Time Ying et al. (2018): Graph Convolutional Neural Networks for Web-Scale Recommender Systems Pal et al. (2020): PinnerSage: Multi-Modal User Embedding Framework for Recommendations at Pinterest Pancha et al. (2022): PinnerFormer: Sequence Modeling for User Representation at Pinterest Zhao et al. (2019): Recommending what video to watch next: a multitask ranking system General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#22
Apr 8, 2024 · 1 hr 35 min
#21: User-Centric Evaluation and Interactive Recommender Systems with Martijn Willemsen
In episode 21 of Recsperts, we welcome Martijn Willemsen, Associate Professor at the Jheronimus Academy of Data Science and Eindhoven University of Technology. Martijn's researches on interactive recommender systems which includes aspects of decision psychology and user-centric evaluation. We discuss how users gain control over recommendations, how to support their goals and needs as well as how the user-centric evaluation framework fits into all of this. In our interview, Martijn outlines the reasons for providing users control over recommendations and how to holistically evaluate the satisfaction and usefulness of recommendations for users goals and needs. We discuss the psychology of decision making with respect to how well or not recommender systems support it. We also dive into music recommender systems and discuss how nudging users to explore new genres can work as well as how longitudinal studies in recommender systems research can advance insights. Towards the end of the episode, Martijn and I also discuss some examples and the usefulness of enabling users to provide negative explicit feedback to the system. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (03:03) - About Martijn Willemsen (15:14) - Waves of User-Centric Evaluation in RecSys (19:35) - Behaviorism is not Enough (46:21) - User-Centric Evaluation Framework (01:05:38) - Genre Exploration and Longitudinal Studies in Music RecSys (01:20:59) - User Control and Negative Explicit Feedback (01:31:50) - Closing Remarks Links from the Episode: Martijn Willemsen on LinkedIn Martijn Willemsen's Website User-centric Evaluation Framework Behaviorism is not Enough (Talk at RecSys 2016) Neil Hunt: Quantifying the Value of Better Recommendations (Keynote at RecSys 2014) What recommender systems can learn from decision psychology about preference elicitation and behavioral change (Talk at Boise State (Idaho) and Grouplens at University of Minnesota) Eric J. Johnson: The Elements of Choice Rasch Model Spotify Web API Papers: Ekstrand et al. (2016): Behaviorism is not Enough: Better Recommendations Through Listening to Users Knijenburg et al. (2012): Explaining the user experience of recommender systems Ekstrand et al. (2014): User perception of differences in recommender algorithms Liang et al. (2022): Exploring the longitudinal effects of nudging on users’ music genre exploration behavior and listening preferences McNee et al. (2006): Being accurate is not enough: how accuracy metrics have hurt recommender systems General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#21
Nov 16, 2023 · 1 hr 45 min
#20: Practical Bandits and Travel Recommendations with Bram van den Akker
In episode 20 of Recsperts, we welcome Bram van den Akker, Senior Machine Learning Scientist at Booking.com. Bram's work focuses on bandit algorithms and counterfactual learning. He was one of the creators of the Practical Bandits tutorial at the World Wide Web conference. We talk about the role of bandit feedback in decision making systems and in specific for recommendations in the travel industry. In our interview, Bram elaborates on bandit feedback and how it is used in practice. We discuss off-policy- and on-policy-bandits, and we learn that counterfactual evaluation is right for selecting the best model candidates for downstream A/B-testing, but not a replacement. We hear more about the practical challenges of bandit feedback, for example the difference between model scores and propensities, the role of stochasticity or the nitty-gritty details of reward signals. Bram also shares with us the challenges of recommendations in the travel domain, where he points out the sparsity of signals or the feedback delay. At the end of the episode, we can both agree on a good example for a clickbait-heavy news service in our phones. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (02:58) - About Bram van den Akker (09:16) - Motivation for Practical Bandits Tutorial (16:53) - Specifics and Challenges of Travel Recommendations (26:19) - Role of Bandit Feedback in Practice (49:13) - Motivation for Bandit Feedback (01:00:54) - Practical Start for Counterfactual Evaluation (01:06:33) - Role of Business Rules (01:11:26) - better cut this section coherently (01:17:48) - Rewards and More (01:32:45) - Closing Remarks Links from the Episode: Bram van den Akker on LinkedIn Practical Bandits: An Industry Perspective (Website) Practical Bandits: An Industry Perspective (Recording) Tutorial at The Web Conference 2020: Unbiased Learning to Rank: Counterfactual and Online Approaches Tutorial at RecSys 2021: Counterfactual Learning and Evaluation for Recommender Systems: Foundations, Implementations, and Recent Advances GitHub: Open Bandit Pipeline Papers: van den Akker et al. (2023): Practical Bandits: An Industry Perspective van den Akker et al. (2022): Extending Open Bandit Pipeline to Simulate Industry Challenges van den Akker et al. (2019): ViTOR: Learning to Rank Webpages Based on Visual Features General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel.kurovski@gmail.com Recsperts Website
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#20
Oct 12, 2023 · 1 hr 41 min
#19: Popularity Bias in Recommender Systems with Himan Abdollahpouri
In episode 19 of Recsperts, we welcome Himan Abdollahpouri who is an Applied Research Scientist for Personalization & Machine Learning at Spotify. We discuss the role of popularity bias in recommender systems which was the dissertation topic of Himan. We talk about multi-objective and multi-stakeholder recommender systems as well as the challenges of music and podcast streaming personalization at Spotify. In our interview, Himan walks us through popularity bias as the main cause of unfair recommendations for multiple stakeholders. We discuss the consumer- and provider-side implications and how to evaluate popularity bias. Not the sheer existence of popularity bias is the major problem, but its propagation in various collaborative filtering algorithms. But we also learn how to counteract by debiasing the data, the model itself, or it's output. We also hear more about the relationship between multi-objective and multi-stakeholder recommender systems. At the end of the episode, Himan also shares the influence of popularity bias in music and podcast streaming at Spotify as well as how calibration helps to better cater content to users' preferences. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (04:43) - About Himan Abdollahpouri (15:23) - What is Popularity Bias and why is it important? (25:05) - Effect of Popularity Bias in Collaborative Filtering (30:30) - Individual Sensitivity towards Popularity (36:25) - Introduction to Bias Mitigation (53:16) - Content for Bias Mitigation (56:53) - Evaluating Popularity Bias (01:05:01) - Popularity Bias in Music and Podcast Streaming (01:08:04) - Multi-Objective Recommender Systems (01:16:13) - Multi-Stakeholder Recommender Systems (01:18:38) - Recommendation Challenges at Spotify (01:35:16) - Closing Remarks Links from the Episode: Himan Abdollahpouri on LinkedIn Himan Abdollahpouri on X Himan's Website Himan's PhD Thesis on "Popularity Bias in Recommendation: A Multi-stakeholder Perspective" 2nd Workshop on Multi-Objective Recommender Systems (MORS @ RecSys 2022) Papers: Su et al. (2009): A Survey on Collaborative Filtering Techniques Mehrotra et al. (2018): Towards a Fair Marketplace: Counterfactual Evaluation of the trade-off between Relevance, Fairness & Satisfaction in Recommender Systems Abdollahpouri et al. (2021): User-centered Evaluation of Popularity Bias in Recommender Systems Abdollahpouri et al. (2019): The Unfairness of Popularity Bias in Recommendation Abdollahpouri et al. (2017): Controlling Popularity Bias in Learning-to-Rank Recommendation Wasilewsi et al. (2016): Incorporating Diversity in a Learning to Rank Recommender System Oh et al. (2011): Novel Recommendation Based on Personal Popularity Tendency Steck (2018): Calibrated Recommendations Abdollahpouri et al. (2023): Calibrated Recommendations as a Minimum-Cost Flow Problem Seymen et al. (2022): Making smart recommendations for perishable and stockout products General Links: Follow me on LinkedIn Follow me on X Send me your comments, questions and suggestions to marcel@recsperts.com Recsperts Website
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#19
Aug 17, 2023 · 1 hr 39 min
#18: Recommender Systems for Children and non-traditional Populations
In episode 18 of Recsperts, we hear from Professor Sole Pera from Delft University of Technology. We discuss the use of recommender systems for non-traditional populations, with children in particular. Sole shares the specifics, surprises, and subtleties of her research on recommendations for children. In our interview, Sole and I discuss use cases and domains which need particular attention with respect to non-traditional populations. Sole outlines some of the major challenges like lacking public datasets or multifaceted criteria for the suitability of recommendations. The highly dynamic needs and abilities of children pose proper user modeling as a crucial part in the design and development of recommender systems. We also touch on how children interact differently with recommender systems and learn that trust plays a major role here. Towards the end of the episode, we revisit the different goals and stakeholders involved in recommendations for children, especially the role of parents. We close with an overview of the current research community. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Introduction (04:56) - About Sole Pera (06:37) - Non-traditional Populations (09:13) - Dedicated User Modeling (25:01) - Main Application Domains (40:16) - Lack of Data about non-traditional Populations (47:53) - Data for Learning User Profiles (57:09) - Interaction between Children and Recommendations (01:00:26) - Goals and Stakeholders (01:11:35) - Role of Parents and Trust (01:17:59) - Evaluation (01:26:59) - Research Community (01:32:37) - Closing Remarks Links from the Episode: Sole Pera on LinkedIn Sole's Website Children and Recommenders KidRec 2022 People and Information Retrieval Team (PIReT) Papers: Beyhan et al. (2023): Covering Covers: Characterization Of Visual Elements Regarding Sleeves Murgia et al. (2019): The Seven Layers of Complexity of Recommender Systems for Children in Educational Contexts Pera et al. (2019): With a Little Help from My Friends: User of Recommendations at School Charisi et al. (2022): Artificial Intelligence and the Rights of the Child: Towards an Integrated Agenda for Research and Policy Gómez et al. (2021): Evaluating recommender systems with and for children: towards a multi-perspective framework Ng et al. (2018): Recommending social-interactive games for adults with autism spectrum disorders (ASD) General Links: Follow me on LinkedIn Follow me on Twitter Send me your comments, questions and suggestions to marcel@recsperts.com Recsperts Website
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#18
Jun 15, 2023 · 1 hr 2 min
#17: Microsoft Recommenders and LLM-based RecSys with Miguel Fierro
In episode 17 of Recsperts, we meet Miguel Fierro who is a Principal Data Science Manager at Microsoft and holds a PhD in robotics. We talk about the Microsoft recommenders repository with over 15k stars on GitHub and discuss the impact of LLMs on RecSys. Miguel also shares his view of the T-shaped data scientist. In our interview, Miguel shares how he transitioned from robotics into personalization as well as how the Microsoft recommenders repository started. We learn more about the three key components: examples, library, and tests. With more than 900 tests and more than 30 different algorithms, this library demonstrates a huge effort of open-source contribution and maintenance. We hear more about the principles that made this effort possible and successful. Therefore, Miguels also shares the reasoning behind evidence-based design to put the users of microsoft-recommenders and their expectations first. We also discuss the impact that recent LLM-related innovations have on RecSys. At the end of the episode, Miguel explains the T-shaped data professional as an advice to stay competitive and build a champion data team. We conclude with some remarks regarding the adoption and ethical challenges recommender systems pose and which need further attention. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Don't forget to follow the podcast and please leave a review (00:00) - Episode Overview (03:34) - Introduction Miguel Fierro (16:19) - Microsoft Recommenders Repository (30:04) - Structure of MS Recommenders (34:16) - Contributors to MS Recommenders (37:10) - Scalability of MS Recommenders (39:32) - Impact of LLMs on RecSys (48:26) - T-shaped Data Professionals (53:29) - Further RecSys Challenges (59:28) - Closing Remarks Links from the Episode: Miguel Fierro on LinkedIn Miguel Fierro on Twitter Miguel's Website Microsoft Recommenders McKinsey (2013): How retailers can keep up with consumers Fortune (2012): Amazon's recommendation secret RecSys 2021 Keynote by Max Welling: Graph Neural Networks for Knowledge Representation and Recommendation Papers: Geng et al. (2022): Recommendation as Language Processing (RLP): A Unified Pretrain, Personalized Prompt & Predict Paradigm (P5) General Links: Follow me on LinkedIn Follow me on Twitter Send me your comments, questions and suggestions to marcel@recsperts.com Recsperts Website
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#17
May 17, 2023 · 1 hr 42 min
#16: Fairness in Recommender Systems with Michael D. Ekstrand
In episode 16 of Recsperts, we hear from Michael D. Ekstrand, Associate Professor at Boise State University, about fairness in recommender systems. We discuss why fairness matters and provide an overview of the multidimensional fairness-aware RecSys landscape. Furthermore, we talk about tradeoffs, methods and receive practical advice on how to get started with tackling unfairness. In our discussion, Michael outlines the difference and similarity between fairness and bias. We discuss several stages at which biases can enter the system as well as how bias can indeed support mitigating unfairness. We also cover the perspectives of different stakeholders with respect to fairness. We also learn that measuring fairness depends on the specific fairness concern one is interested in and that solving fairness universally is highly unlikely. Towards the end of the episode, we take a look at further challenges as well as how and where the upcoming RecSys 2023 provides a forum for those interested in fairness-aware recommender systems. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. (00:00) - Episode Overview (02:57) - Introduction Michael Ekstrand (17:08) - Motivation for Fairness-Aware Recommender Systems (25:45) - Overview and Definition of Fairness in RecSys (46:51) - Distributional and Representational Harm (53:59) - Relationship between Fairness and Bias (01:04:43) - Tradeoffs (01:13:36) - Methods and Metrics for Fairness (01:28:06) - Practical Advice for Tackling Unfairness (01:32:24) - Further Challenges (01:35:24) - RecSys 2023 (01:38:29) - Closing Remarks Links from the Episode: Michael Ekstrand on LinkedIn Michael Ekstrand on Mastodon Michael's Website GroupLens Lab at University of Minnesota People and Information Research Team (PIReT) 6th FAccTRec Workshop: Responsible Recommendation NORMalize: The First Workshop on Normative Design and Evaluation of Recommender Systems ACM Conference on Fairness, Accountability, and Transparency (ACM FAccT) Coursera: Recommender Systems Specialization LensKit: Python Tools for Recommender Systems Chris Anderson - The Long Tail: Why the Future of Business Is Selling Less of More Fairness in Recommender Systems (in Recommender Systems Handbook) Ekstrand et al. (2022): Fairness in Information Access Systems Keynote at EvalRS (CIKM 2022): Do You Want To Hunt A Kraken? Mapping and Expanding Recommendation Fairness Friedler et al. (2021): The (Im)possibility of Fairness: Different Value Systems Require Different Mechanisms For Fair Decision Making Safiya Umoja Noble (2018): Algorithms of Oppression: How Search Engines Reinforce Racism Papers: Ekstrand et al. (2018): Exploring author gender in book rating and recommendation Ekstrand et al. (2014): User perception of differences in recommender algorithms Selbst et al. (2019): Fairness and Abstraction in Sociotechnical Systems Pinney et al. (2023): Much Ado About Gender: Current Practices and Future Recommendations for Appropriate Gender-Aware Information Access Diaz et al. (2020): Evaluating Stochastic Rankings with Expected Exposure Raj et al. (2022): Fire Dragon and Unicorn Princess; Gender Stereotypes and Children's Products in Search Engine Responses Mitchell et al. (2021): Algorithmic Fairness: Choices, Assumptions, and Definitions Mehrotra et al. (2018): Towards a Fair Marketplace: Counterfactual Evaluation of the trade-off between Relevance, Fairness & Satisfaction in Recommender Systems Raj et al. (2022): Measuring Fairness in Ranked Results: An Analytical and Empirical Comparison Beutel et al. (2019): Fairness in Recommendation Ranking through Pairwise Comparisons Beutel et al. (2017): Data Decisions and Theoretical Implications when Adversarially Learning Fair Representations Dwork et al. (2018): Fairness Under Composition Bower et al. (2022): Random Isn't Always Fair: Candidate Set Imbalance and Exposure Inequality in Recommender Systems Zehlike et al. (2022): Fairness in Ranking: A Survey Hoffmann (2019): Where fairness fails: data, algorithms, and the limits of antidiscrimination discourse Sweeney (2013): Discrimination in Online Ad Delivery: Google ads, black names and white names, racial discrimination, and click advertising Wang et al. (2021): User Fairness, Item Fairness, and Diversity for Rankings in Two-Sided Markets General Links: Follow me on Twitter: https://twitter.com/MarcelKurovski Send me your comments, questions and suggestions to marcel@recsperts.com Podcast Website: https://www.recsperts.com/
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#16
Apr 27, 2023 · 1 hr 19 min
#15: Podcast Recommendations in the ARD Audiothek with Mirza Klimenta
In episode 15 of Recsperts, we delve into podcast recommendations with senior data scientist, Mirza Klimenta. Mirza discusses his work on the ARD Audiothek, a public broadcaster of audio-on-demand content, where he is part of pub. Public Value Technologies, a subsidiary of the two regional public broadcasters BR and SWR. We explore the use and potency of simple algorithms and ways to mitigate popularity bias in data and recommendations. We also cover collaborative filtering and various approaches for content-based podcast recommendations, drawing on Mirza's expertise in multidimensional scaling for graph drawings. Additionally, Mirza sheds light on the responsibility of a public broadcaster in providing diversified content recommendations. Towards the end of the episode, Mirza shares personal insights on his side project of becoming a novelist. Tune in for an informative and engaging conversation. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. (00:00) - Episode Overview (01:43) - Introduction Mirza Klimenta (08:06) - About ARD Audiothek (21:16) - Recommenders for the ARD Audiothek (30:03) - User Engagement and Feedback Signals (46:05) - Optimization beyond Accuracy (51:39) - Next RecSys Steps for the Audiothek (57:16) - Underserved User Groups (01:04:16) - Cold-Start Mitigation (01:05:06) - Diversity in Recommendations (01:07:50) - Further Challenges in RecSys (01:10:03) - Being a Novelist (01:16:07) - Closing Remarks Links from the Episode: Mirza Klimenta on LinkedIn ARD Audiothek pub. Public Value Technologies Implicit: Fast Collaborative Filtering for Implicit Datasets Fairness in Recommender Systems: How to Reduce the Popularity Bias Papers: Steck (2019): Embarrasingly Shallow Auoencoders for Sparse Data Hu et al. (2008): Collaborative Filtering for Implicit Feedback Datasets Cer et al. (2018): Universal Sentence Encoder General Links: Follow me on Twitter: https://twitter.com/MarcelKurovski Send me your comments, questions and suggestions to marcel@recsperts.com Podcast Website: https://www.recsperts.com/
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#15
Mar 15, 2023 · 1 hr 43 min
#14: User Modeling and Superlinked with Daniel Svonava
In episode number 14 of Recsperts we talk to Daniel Svonava, CEO and Co-Founder of Superlinked, delivering user modeling infrastructure. In his former role he was a senior software engineer and tech lead at YouTube working on ad performance prediction and pricing. We discuss the crucial role of user modeling for recommendations and discovery. Daniel presents two examples from YouTube’s ad performance forecasting to demonstrate the bandwidth of use cases for user modeling. We also discuss sources of information that fuel user models and additional personlization tasks that benefit from it like user onboarding. We learn that the tight combination of user modeling with (near) real-time updates is key to a sound personalized user experience. Daniel also shares with us how Superlinked provides personalization as a service beyond ecommerce-centricity. Offering personalized recommendations of items and people across various industries and use cases is what sets Superlinked apart. In the end, we also touch on the major general challenge of the RecSys community which is rebranding in order to establish a more positive image of the field. Enjoy this enriching episode of RECSPERTS - Recommender Systems Experts. Chapters: (03:35) - Introduction Daniel Svonava (10:18) - Introduction to User Modeling (17:52) - User Modeling for YouTube Ads (35:43) - Real-Time Personalization (57:29) - ML Tooling for User Modeling and Real-Time Personalization (01:07:41) - Superlinked as a User Modeling Infrastructure (01:31:22) - Rebranding RecSys as Major Challenge (01:37:40) - Final Remarks Links from the Episode: Daniel Svonava on LinkedIn Daniel Svonava on Twitter Superlinked - User Modeling Infrastructure The 2023 MAD (Machine Learning, Artificial Intelligence, Data Science) Landscape Eric Ries: The Lean Startup Rob Fitzpatrick: The Mom Test Papers: Liu et al. (2022): Monolith: Real Time Recommendation System With Collisionless Embedding Table RSPapers Collection General Links: Follow me on Twitter: https://twitter.com/MarcelKurovski Send me your comments, questions and suggestions to marcel@recsperts.com Podcast Website: https://www.recsperts.com/
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