16. The system of claim 13 , wherein demoting the second images in the order in the first set relative to the first images in the first set comprises: for each second image included in only one of the second set or third set, demoting the second image in the first set in proportion to its ordinal position in the order in the other of the second set or third of images in which it is included, wherein the lower the ordinal position the higher the relevance of the image to the query.
16. The system of claim 13 , wherein demoting the second images in the order in the first set relative to the first images in the first set comprises: for each second image included in only one of the second set or third set, demoting the second image in the first set in proportion to its ordinal position in the order in the other of the second set or third of images in which it is included, wherein the lower the ordinal position the higher the relevance of the image to the query. 17. The system of claim 16 , wherein demoting the second images in the order in the first set relative to the first images in the first set comprises: for each second image included in both of the second set and third set, demoting the second image in the first set in proportion to its highest of the ordinal positions in the orders in the second set and third sets, wherein the lower the ordinal position the higher the relevance of the image to the query.