Questions about Weighting Schemes project

Sourav Saha souravsaha.juit at gmail.com
Thu Apr 4 10:12:14 BST 2019


Hi,
I was going through the Xapian code base of different weighting schemes. In
the lmweight code, I found out that we are returning non-negative numbers
from get_maxpart, get_sumpart methods. Is this to avoid negative weight?
Also in the Language Model with Jelinek Mercer Smoothing (LM-JM)
implementation, I don't see any idf effect involved in that equation. The
LM-JM equation looks something like this:
 *(LAMBDA)* MLE(t,d) + (1-LAMBDA) * MLE(t,c)*
However, if we bind it with idf, it will look like :

*1 + ((LAMBDA) / (1-LAMBDA) * (MLE(t,d) / MLE(t,c))) *
which is widely used everywhere. I am planning to patch an improved
representation of LM-JM with the idf effect shortly. Kindly let me know for
any concerns.

Thanks and Regards,
-Sourav
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