On a sidewalk, tall man in a black shirt and a police officer with their backs to the viewer walk past a man in a white t-shirt, black shorts, and sandals.
A cop watches some suspects in the middle of a city.
The police officer may not be watching anyone.  The others may not be suspects. Not all sidewalks are in the city.
exists s1 s2 s3 s4 x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12 x13 x14 x15.(n_walk(x10) & of(x10,x11) & n_viewer(x11) & on(x1,x2) & rel(x2,x3) & subset_of(x6,x3) & with(x6,x8) & subset_of(x15,x8) & n_sandal(x15) & subset_of(x9,x8) & to(x9,x10) & past(x10,x12) & in(x12,x13) & rel(x13,x14) & n_shorts(x14) & a_black(s4) & Theme(s4,x14) & n_t-shirt(x13) & a_white(s3) & Theme(s3,x13) & n_man(x12) & n_back(x9) & of(x9,x1) & n_thing(x1) & n_officer(x6) & of(x6,x7) & n_police(x7) & subset_of(x4,x3) & in(x4,x5) & n_shirt(x5) & a_black(s2) & Theme(s2,x5) & n_man(x4) & a_tall(s1) & Theme(s1,x4) & n_sidewalk(x2) & n_event(x1))
exists e1 x1 x2 x3 x4.(n_middle(x3) & in(e1,x3) & of(x3,x4) & n_city(x4) & Theme(e1,x2) & Actor(e1,x1) & v_watch(e1) & n_suspect(x2) & n_cop(x1))