... comparison, and following Lil-lis et al. (2006) and Lee (1997), compute it in thefollowing way. First, we normalize each score sias norm(si) =si−min(s)max(s)−min(s), where max(s) and min(s) ... there are almost certainly othercombination approaches worth investigating. Somepossible approaches include simple linear combi-nations of the putative term frequencies, combina-tions of one ... Here again, a linear combinationof scores will fail, as will rank-based interleaving. In the latter case, we will alternate between taking aplausible document from system A and an inevitablyworse...