21. The system of claim 16 , wherein generating a ranking for the candidate scoring functions in the group based at least in part on the user input comprises: adding the user input to a set of multiple pair-wise user comparisons of scoring functions; and generating the ranking for the candidate scoring functions in the group based at least in part on the set of multiple pair-wise user comparisons.
21. The system of claim 16 , wherein generating a ranking for the candidate scoring functions in the group based at least in part on the user input comprises: adding the user input to a set of multiple pair-wise user comparisons of scoring functions; and generating the ranking for the candidate scoring functions in the group based at least in part on the set of multiple pair-wise user comparisons. 22. The system of claim 21 , wherein the search results ordered according to scores from the first candidate scoring function constitute a first order, and the operations comprise: receiving a notification that the first candidate scoring function has been modified; applying the modified first scoring function to the search results to determine modified scores for the search results and to generate a second order for the search results according to the modified scores; determining that the first order and the second order are different; and modifying the ranking for the candidate scoring functions in the group so that the modified ranking for the candidate scoring functions in the group does not reflect the user input.