Add a Google paper proposed WARP loss to the recommendation system.

README.md

@@ -191,6 +191,7 @@ P.P.S, Looking for guides and interviews on applying ML? 👉[`applyingML`](http
 32. [Self-supervised Learning for Large-scale Item Recommendations](https://arxiv.org/abs/2007.12865) ([Paper](https://arxiv.org/pdf/2007.12865.pdf)) `Google`
 33. [Mixed Negative Sampling for Learning Two-tower Neural Networks in Recommendations](https://research.google/pubs/pub50257/) ([Paper](https://storage.googleapis.com/pub-tools-public-publication-data/pdf/b9f4e78a8830fe5afcf2f0452862fb3c0d6584ea.pdf)) `Google`
 32. [Personalized Channel Recommendations in Slack](https://slack.engineering/personalized-channel-recommendations-in-slack/) `Slack`
+32. [Learning to Rank Recommendations with the k -Order Statistic Loss](https://dl.acm.org/doi/10.1145/2507157.2507210) ([Paper](https://dl.acm.org/doi/pdf/10.1145/2507157.2507210)) `Google`
 33. [Deep Retrieval: End-to-End Learnable Structure Model for Large-Scale Recommendations](https://arxiv.org/abs/2007.07203) ([Paper](https://arxiv.org/pdf/2007.07203.pdf)) `ByteDance`
 34. [Future Data Helps Training: Modeling Future Contexts for Session-based Recommendation]() ([Paper](https://arxiv.org/pdf/1906.04473.pdf)) `Tencent`
 35. [Using AI to Help Health Experts Address the COVID-19 Pandemic](https://ai.facebook.com/blog/using-ai-to-help-health-experts-address-the-covid-19-pandemic/) `Facebook`