2. The system of claim 1 , wherein the intermingler is to: select an item from the first set and position it in the list of search results; determine a first new ratio between items from the first set in the list of search results and items from the second set in the list of search results, assuming a next selected item is from the first set; determine a second new ratio between items from the first set in the list of search results and items from the second set in the list of search results, assuming the next selected item is from the second set; compare a first difference between the first new ratio and the target ratio with a second difference between the second new ratio and the target ratio; and select a next item for positioning in the list of search results from the first set or from the second set, based on a result of the comparing.
3. The system of claim 2 , wherein the intermingler is to: determine that the first difference is less than the second difference; and select the next item from the first set of items in the first format and position it in the list of search results as the next item.