[SOLR-15569] MultipleAdditiveTreesModel does not split as expected when the node value equals the split threshold

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 9.0, 8.9
• Component/s: contrib - LTR
• Assignee: Alessandro Benedetti
• Reporter: Spyros Kapnissis
• Created: 28/Jul/21 18:52
• Updated: 25/Feb/24 00:00

Description

As discussed on the mailing list: https://lists.apache.org/thread.html/r23e10a021445e7bcf26ce578320304bd77165bc0c2136621f7a6225e%40%3Cusers.solr.apache.org%3E , MultipleAdditiveTreesModel does not split as expected when the value of the tree node is equal to the threshold, but splits to the left instead of the right. This can cause the final score of the model to change significantly.

This issue affects especially categorical or boolean features that take on integer values. eg. if a feature can take on 0 or 1 and the left/right split is set to 1.0, the right path will never be evaluated.

I will try to follow up with a test model that showcases the issue.

Issue Links

• is related to: SOLR-8542 Integrate Learning to Rank into Solr
• links to: GitHub Pull Request #242