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Systems)
Problem)
formula4on)
Machine)Learning)
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Recommender Systems-Machine Learning and Artificial Intelligence-Lecture Slides, Slides of Machine Learning
This lecture was delivered by Dr. Ramya Riya at Ankit Institute of Technology and Science. This lecture is part of lecture series on Machine Learning and Artificial Intelligence course. It includes: Recommender, System, Problem, Formulation, Predicting, Movie, Ratings, Content-based, Feature, vector, Optimization, Objective, Gradient, Descent
Typology: Slides
2011/2012
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Recommender
Systems
Problem
formula4on
Machine Learning
Example: Predic/ng movie ra/ngs
User rates movies using one to five stars
Movie Alice (1) Bob (2) Carol (3) Dave (4)
Love at last
Romance forever
Cute puppies of love
Nonstop car chases
Swords vs. karate
= no. users = no. movies = 1 if user has rated movie = ra4ng given by user to movie (defined only if )
Content-‐based recommender systems
Movie Alice (1) Bob (2) Carol (3) Dave (4) (romance) (ac/on) Love at last 5 5 0 0 0.9 0 Romance forever 5?? 0 1.0 0. Cute puppies of love? 4 0? 0.99 0 Nonstop car chases 0 0 5 4 0.1 1. Swords vs. karate 0 0 5? 0 0.
For each user , learn a parameter. Predict user as
ra4ng movie with stars.
Problem formula/on
if user has rated movie (0 otherwise)
ra4ng by user on movie (if defined)
= parameter vector for user
= feature vector for movie
For user , movie , predicted ra4ng:
= no. of movies rated by user
To learn :
Op/miza/on algorithm:
Gradient descent update:
Recommender
Systems
Machine Learning
Collabora4ve
filtering
Problem mo/va/on Movie Alice (1) Bob (2) Carol (3) Dave (4) (romance) (ac/on) Love at last 5 5 0 0?? Romance forever 5?? 0?? Cute puppies of love
Nonstop car chases
Swords vs. karate 0 0 5???
Op/miza/on algorithm Given , to learn : Given , to learn :
Recommender
Systems
Machine Learning
Collabora4ve
filtering algorithm
Collabora/ve filtering op/miza/on objec/ve
Given , es4mate : Given , es4mate : Minimizing and simultaneously:
Recommender
Systems
Machine Learning
Vectoriza4on:
Low rank matrix
factoriza4on
Collabora/ve filtering
Movie Alice (1) Bob (2) Carol (3) Dave (4) Love at last 5 5 0 0 Romance forever 5?? 0 Cute puppies of love
Nonstop car chases
Swords vs. karate 0 0 5?