Formally, we define for ith entity the popularity variable q i (u) = Σ m I(u m = i) and the potential for EP factor Ψ EP i (u) as follows: The parameter α > 0 is initially fit from Freebase entities and then finetuned with TAC 2014 dataset to reflect real-world distributions.
most entities have only a small number of variants and are mentioned only a few times.