Table 2 Overview of the link predictors used in the experiments. In the table, \(A = N(x)\cap N(y)\) and \(c = U\cup V\). (For the other definitions, refer to Sects. 2 and 3)

CN-based

Common Neighbors (CN)[20]

\(|N(x)\cap N(y)|\)

CRA[32]

\(\sum _{a\in A} \frac{|N(a)\cap A|}{|N(a)|}\)

L3-based

L3[18]

\(\sum _{U,V} \frac{1}{\sqrt{|N(u_{i})|\cdot |N(v_{j})|}}\)

CH2_L3 (CH2)[23]

\(\sum _{U,V} \frac{\sqrt{(1+|N(u)\cap c|)\cdot (1+|N(v)\cap c|)}}{\sqrt{(1+|N(u)\backslash c)\backslash \{x,y\}|)\cdot (1+|N(v)\backslash c)\backslash \{x,y\}|)}}\)

Sim[33]

\(\sum _{V} \frac{|N(v)\cap N(x)|}{|N(v)\cup N(x)|} + \sum _{U} \frac{|N(u)\cap N(y)|}{|N(u)\cup N(y)|}\)

NormalizedL3 (L3N) predictors

Plug in either \(f_1\) or \(f_2\) into Formula (6) or (7)

control

rand

Rank the edges uniformly at random