A cowboy gets thrown from a horse during the rodeo competition.
The cowboy did not fall of the horse at the competition.
A cowboy is a general statement while The cowboy is allot more specific, also get thrown is very different than  did not fall.
exists e1 p1 x1 x3 x4.(n_competition(x3) & of(x3,x4) & n_rodeo(x4) & exists e2 x2.(during(e2,x3) & from(e2,x2) & n_horse(x2) & Theme(e2,x1) & v_throw(e2)) & Topic(e1,p1) & Actor(e1,x1) & v_get(e1) & n_cowboy(x1))
exists x1 x2 x3.(n_competition(x3) & n_horse(x2) & n_cowboy(x1) & -exists e1.(of(e1,x2) & at(x2,x3) & Actor(e1,x1) & v_fall(e1)))