In Jira issue
LUCENE-9537, basic functionality from the Indri search engine (http://lemurproject.org/indri.php) was added to Lucene. With that functionality in place, we would love to build upon that to add additional Indri queries and an Indri query parser to Lucene to broaden the Indri functionality within Lucene. In this patch, I have added the Indri NOT, the INDRI OR, and the Indri WeightedSum functionality. I have also included an IndriQueryParser for accessing this functionality. More information on these query operators can be seen here: https://sourceforge.net/p/lemur/wiki/Belief%20Operations/ and here: https://sourceforge.net/p/lemur/wiki/Indri%20Query%20Language%20Reference/.
I would be very excited to work with the Lucene community again to try to add this functionality. I am open to suggestions, and I am happy to make any changes that might be suggested. Thank you!