Another man in a gray sweatshirt also rides a horse.
There is a second person riding a pony down the street.
The fact that a man rides a horse doesn't imply second person riding a pony.
exists e1 s1 s2 x1 x2 x3 x4.(n_man(x1) & a_also(s2) & Manner(e1,s2) & Theme(e1,x4) & Actor(e1,x2) & v_ride(e1) & n_horse(x4) & in(x2,x3) & n_sweatshirt(x3) & a_gray(s1) & Theme(s1,x3) & n_man(x2) & -(x2 = x1))
exists p1 x1 x5.(n_street(x5) & exists e1 s1 x2 x3 x4.((x1 = x2) & down(e1,x5) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & n_pony(x4) & (x2 = x3) & n_person(x2) & a_second(s1) & Theme(s1,x2)))