a man wearing black rides a unicycle.
The man riding the unicycle is performing tricks.
He can't be said to be performing tricks; he may just be riding.
exists x1 x2.(a_topic(x1) & all x3.(n_unicycle(x3) -> exists e1 s1 x4.(Theme(e1,x4) & Actor(e1,x2) & v_wear(e1) & for(x4,x3) & n_ride(x4) & a_black(s1) & Theme(s1,x4))) & (x1 = x2) & n_man(x1))
exists e2 e1 x1 x2 x3 x4.(n_unicycle(x3) & n_man(x1) & Theme(e2,x4) & Actor(e2,x1) & v_perform(e2) & n_trick(x4) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & (x1 = x2))