You may know of OpenSource Connections - we built and maintain the Elasticsearch Learning to Rank plugin https://github.com/o19s/elasticsearch-learning-to-rank . We're running training on LTR from 20-23 October https://opensourceconnections.com/training/hello-ltr-learning-to-rank/ and tickets are on sale at the earlybird rate now!
You'll learn from working relevance engineers how to interact with the Solr & Elasticsearch Learning to Rank plugins, use machine learning to optimize relevance, avoid common pitfalls on Learning to Rank projects and more, with practical exercises and labs. Some familiarity with Elasticsearch and Solr is expected.
If you don't know much about LTR and machine learning for search, do check out this blog post https://opensourceconnections.com/blog/2017/02/24/what-is-learning-to-rank/