Matrix Factorization
Matrix factorization is a popular technique used in recommendation systems to predict users' preferences for items based on their past interactions. The main idea behind matrix factorization is to decompose the user-item interaction matrix into two or more lower-dimensional matrices, which can then be used to estimate the missing entries in the original matrix.
To train a matrix factorization model, you need to minimize the difference between the estimated ratings and the actual ratings in the user-item interaction matrix. This is typically done by optimizing an objective function, such as the mean squared error (MSE) or the regularized mean squared error (RMSE), using gradient descent or alternative optimization algorithms.
The most common matrix factorization techniques are Singular Value Decomposition (SVD), Non-negative Matrix Factorization (NMF), and Alternating Least Squares (ALS). Each of these techniques has its own advantages and trade-offs in terms of computational complexity, scalability, and accuracy.