I'm not that impressed, am i missing something? Looks like pre-indexed search matched with full-text search??
Re:How Google Book Search Got Lost
by greglindahl on Tuesday April 11, 2017 @03:16PM
(#14091439)
It's an index of concepts that appear in a sentence with dates. The blog post shows an example of how this type of index surfaces important dates for the concept 'Gregorian Calendar'.
https://blog.archive.org/2016/02/09/how-will-we-explore-book...
https://books.archivelab.org/dateviz/