Group performs a dance together.
Ballet dancers are gliding.
A dancing group need not consist of ballet dancers only.
exists e1 s1 x1 x2.(ne_org_group(x1) & a_together(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_dance(x2))
exists e1 x1 x2.(Actor(e1,x1) & v_glide(e1) & n_dancer(x1) & (x1 = x2) & ne_nam_ballet(x2))