Kairos: Numerically Robust News Recommendation under Item Cold-Start via Cholesky-based LinUCB
This work addresses the item cold-start problem in regional news recommendation, which arises from short news lifecycles and shallow article pools. To tackle this challenge, the authors propose an enhanced LinUCB online contextual recommendation method that replaces the Sherman–Morrison formula with a rank-1 update mechanism based on Cholesky decomposition, thereby improving the numerical stability and robustness of covariance matrix estimation. Additionally, Matryoshka representation learning is integrated to reduce inference latency. Experimental results using the Tagesschau API demonstrate that the proposed approach achieves a favorable trade-off between efficiency and accuracy under data-scarce conditions, delivering a 4.85× speedup in inference with negligible degradation in ranking performance—making it well-suited for environments constrained by limited computational resources and sparse data.