Table 1 Notations of group establishing algorithm

$N_i^{\mathrm{open}}/N_i^{\mathrm{close}}/\mathrm{Den}\left(i\right)$

Open set of neighbors of node i/closed set of neighbors of node i/density of node i

a _i

The number of neighbors of node i which are in the same group with node i

G _i

The ID number of GM which node i belongs to

mG _i

The ID number of GM which node i is ready to join

BoolP _i

Denotes the state that node i must change another group to meet the group condition

Pointer S _i

Points to one of node i's neighbors which is invited to join the group which node i belongs to

Pointer L _i

Points to a certain node which node i accepts its invitation and agrees to join its group