??? wtf ( k 1 + 1 ) k 1 ( ( 1 - b ) + b wdl avwdl ) + wtf ??? log ( N n ) + w cd 1 k cd + b cd CD + b ud UD b cd + b ud + W ( t ) + W ( l d , l q ) ( 5 ) In an embodiment, the weight of the language prior can be considered as part of the static rank of the document, similar to file type priors, but in fact depends on the query, because the feature itself is a function of both query and document la