How much does time weigh?
As Miles wrote yesterday, our paper was accepted to SIGIR 2011. The idea that time has an impact in ranking documents is not new; the problem seems to be to know when to take it into consideration. For example, while Li and Croft showed improvements in ranking when incorporating the notion of recency, we found that the algorithm degrades performance of non-temporal queries. (This is obvious, in a sense: if a ranking algorithm is biased toward more recent documents, and recency is not important for a given query, it will de-emphasize otherwise well-matching documents, thereby reducing MAP.)