An elderly man holds the hands of a boy in a swimming trunks.
A grandfather is teaching his grandson how to swim.
Just because an elderly man holds a boy's hand doesn't mean he is the boy's grandfather. Just because the boy is in swimming trunks doesn't mean he is being taught how to swim.
exists e1 s1 x1 x2 x3 x4 x5.(n_hand(x2) & Theme(e1,x2) & Actor(e1,x1) & v_hold(e1) & of(x2,x3) & in(x3,x4) & n_trunk(x4) & of(x4,x5) & n_swimming(x5) & n_boy(x3) & n_man(x1) & a_elderly(s1) & Theme(s1,x1))
exists e1 p1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_teach(e1) & Topic(x2,p1) & exists e2.(Actor(e2,x2) & v_swim(e2)) & n_grandson(x2) & of(x2,x1) & n_male(x1) & n_grandfather(x1))