To overcome this limitation, in (Fang and Zhai, 2006), we proposed a set of semantic term matching constraints and modified the previously derived axiomatic functions to make them satisfy these additional constraints.
the primitive weighting function is generalized as where s(q, d) is a semantic similarity function between two terms q and d, and f is a monotonically increasing function defined as where β is a parameter that regulates the weighting of the original query terms and the semantically similar terms.