A fisherman fishes at the bank of a foggy river.
A fisherman fishes by a foggy river trying to catch food for dinner.
You cannot infer that the fisherman is trying to catch food just because he is fishing at a foggy river.
exists e1 s1 x1 x2 x3.(n_bank(x2) & at(e1,x2) & of(x2,x3) & n_river(x3) & a_foggy(s1) & Theme(s1,x3) & Actor(e1,x1) & v_fish(e1) & n_fisherman(x1))
exists e1 e2 p1 s1 x1 x2 x3.(by(e1,x2) & Topic(e2,p1) & Actor(e2,x3) & v_try(e2) & exists e3 x4 x5.(for(e3,x5) & n_dinner(x5) & Theme(e3,x4) & Actor(e3,x3) & v_catch(e3) & n_food(x4)) & (x2 = x3) & n_river(x2) & a_foggy(s1) & Theme(s1,x2) & Actor(e1,x1) & v_fish(e1) & n_fisherman(x1))