Recommendation Systems (RecSys)
A one-stop shop for all things RecSys.
📌 Table of Contents 
    
      
        Introduction
      
      
    
        overview; retrieval; ranking
      
    
      
        Candidate Generation
      
      
    
        notation; content-based filtering; code deep-dive; collaborative filtering; code deep-dive; retrieval
      
    
      
         Ranking / Scoring
      
      
    
    
          overview; scoring with the candidate generator?; objective function for scoring; position/selection bias
      
    
      
        Re-ranking
      
      
    
    
          
          overview; freshness; diversity; fairness
      
    
      
        Calibration
      
      
    
    
      
      platt scaling; isotonic regression; Bayesian calibration
      
    
      
        Popular Architectures
      
      
   
    
     
        Wide and Deep; Deep and Cross; DCN V2; NCF; DeepFM; AutoInt; DLRM; DHEN; GDCN; Two Towers
      
    
      
        Search
      
      
  
   
        lexical search; semantic search; hybrid search
      
    
      
        Building a Music Recommendation System using PySpark
      
      
    
          code deep-dive; data pre-processing; data aggregation; data split; spin up your model!
      
    
      
        Evaluation Metrics and Loss Functions
      
      
      
          evaluating candidate generation; evaluating candidate ranking; A/B testing; loss functions
      
    
      
       Content Moderation for Recommender Systems
      
      
      
          videos, text, and image moderation; early and late moderation
      
    
      
       GNNs for Recommender Systems
      
      
      
          GraphSage; Edge GNNs; use-cases
      
    
      
       Transformers for Recommender Systems
      
      
      
          PinnerFormer; ItemSage
      
    
      
       Challenges of Building a Recommender System
      
      
    
       
      
          result reproducibility; offline-online mismatch; oscillating outputs; slow convergence
      
    
      
        Summary of Relevant Papers
      
      
      
          popular recommendation systems in production demystified
      
    
      
        Biases in Recommender Systems
      
      
      
          clickbait bias; duration bias; position bias; popularity bias; measuring and mitigating positional bias; single-interest bias
      
    
      
        Cold Start Problem
      
      
      
          types of cold start; mitigation strategies
      
    
      
        Multi-Armed Bandit
      
      
      
          exploration; exploitation; contextual bandit
      
    
      
        Multi-Objective Optimization
      
      
    
          re-ranking with MOO; MOO vs. MAB
      
    📖 References
    
        - Google's course on Recommendation Systems
        - Coursera: Music Recommender System Project
        - Coursera: DeepLearning.AI's specialization
        - Recommender system from learned embeddings
        - Google's Recommendation Systems Developer Crash Course
        - ALS introduction by Sophie Wats
        - Matrix Factorization
        - Recommendation System for E-commerce using Alternating Least Squares (ALS) on Apache Spark
        - Personalized Re-ranking for Recommendation
         - Dot Product Wiki
    
    📝 Citation 
    
        If you found our work useful, please cite it as:
   
{
  author        = {Chadha, Aman and Jain, Vinija},
  title         = {Recommender Systems Primer},
  howpublished  = {\url{https://www.aman.ai}},
  year          = {2022},
  note          = {Accessed: 2022-07-01},
  url           = {www.vinija.ai}
}
A. Chadha, V. Jain, Notes for Recommendation Systems https://www.aman.ai, 2022, Accessed: July 1 2022.