We address the challenge of ranking recommendation lists based on click feedback by efficiently encoding similarities among users and among items. The key challenges are threefold: (1) combinatorial number of lists; (2) sparse feedback and (3) context dependent recommendations. We propose the CGPRANK algorithm, which ex- ploits prior information specified in terms of a Gaussian process kernel function, which allows to share feedback in three ways: Between positions in a list, between items, and between contexts. Under our model, we provide strong performance guarantees and empirically evaluate our algorithm on data from two large scale recommendation tasks: Yahoo! news article recommendation, and Google books. In our experiments, our CGPRANK approach significantly outperforms state-of-the-art multi-armed bandit and learning-to-rank methods, with an 18% increase in clicks.

@inproceedings{vanchinathan14explore,
	author = {Hastagiri Vanchinathan and Isidor Nikolic and Fabio {De Bona} and Andreas Krause},
	booktitle = {Proc. ACM Recommender Systems Conference (RecSys)},
	title = {Explore-Exploit in Top-N Recommender Systems via Gaussian Processes},
	year = {2014}}