Protesters joining on a city street.
There are protestors gathering outside.
There being a city street implies they are outside.
exists e1 x1 x2 x3 x4.(a_topic(x1) & on(e1,x3) & n_street(x3) & of(x3,x4) & n_city(x4) & Actor(e1,x2) & v_join(e1) & (x1 = x2) & n_protester(x1))
exists p1 x1 e1 s1 x2 x3.((x1 = x2) & a_outside(s1) & Manner(e1,s1) & Actor(e1,x3) & v_gather(e1) & (x2 = x3) & n_protestor(x2))