I also bought the book (it’s Relevant not Relevance BTW), that one and Deep Learning for Search were invaluable when building a news search engine a few years ago (right before and in the middle of the pandemic).

Can confirm this book is excellent.

It's one I point people at all the time when they ask me why something isn't working as expected in any standard search tool, and something I reference from time to time to refresh my own knowledge.

Well worth the money.

Thank you! It's a bit old now, but I think the principles in it are still valid :)