
$\u3008{n}_{\mathit{cb}}\u3009$

${\sigma}_{b}$

$\u3008{n}_{\mathit{cg}}\u3009$

${\sigma}_{g}$


${d}_{uv}=2$

9.5 (0.2)

0.02

1.12 (0.61)

0.05

u→v

12.9 (0.16)

0.04

1.1 (0.6)

0.08

u↔v

18.5 (0.06)

0.04

1.67 (0.44)

0.11

Simple closure

18.2 (0.09)

0.04

1.81 (0.45)

0.1

Double closure

23.4 (0.03)

0.05

2.2 (0.36)

0.12

 Single and double closure refers respectively to new links u→v and u↔v that close triangles. The similarity is measured by the number of common books ${n}_{\mathit{cb}}$ or groups ${n}_{\mathit{cg}}$, and by the corresponding cosine similarities ${\sigma}_{b}$ and ${\sigma}_{g}$. The numbers in parenthesis give the probability to have similarity equal to 0.