Masked protester surrounded by the police.
The police and the protester are on a trapeeze.
One cannot be surrounded by the police and on a trapeze simultaneously.
exists e1 x1 x2 x3.(n_police(x3) & Actor(e1,x3) & Theme(e1,x1) & v_surround(e1) & n_protester(x1) & (x1 = x2) & ne_nam_masked(x2))
exists p1 x1 x2 x3.(n_protester(x3) & n_police(x2) & exists x4.(on(x1,x4) & n_trapeeze(x4)) & subset_of(x3,x1) & subset_of(x2,x1))