keep user profiles maybe with cookies or by encouraging sign-ups and then use NMF https://en.wikipedia.org/wiki/Non-negative_matrix_factorization https://en.wi

keep user profiles maybe with cookies or by encouraging sign-ups and then use NMF https://en.wikipedia.org/wiki/Non-negative_matrix_factorization https://en.wikipedia.org/wiki/Non-negative_matrix_factorizat...