People walking their dogs along a riverbank.
People and their dogs swimming in a river.
Walking and swimming are different actions
exists e1 x1 x2 x3 x4.(a_topic(x1) & along(e1,x4) & n_riverbank(x4) & Theme(e1,x3) & Actor(e1,x2) & v_walk(e1) & n_dog(x3) & of(x3,x1) & n_thing(x1) & (x1 = x2) & n_people(x1))
exists s1 x1 x2 x3 x4.(a_topic(s1) & subset_of(x2,s1) & in(x2,x4) & n_river(x4) & n_swimming(x2) & of(x2,x3) & n_dog(x3) & of(x2,x1) & n_thing(x1) & subset_of(x1,s1) & n_people(x1))