Older person is helping a child on ice skates.
A child is teaching an older person to skate.
The child cannot be teaching an older person to skate, if the older person is helping the child on skates.
exists e1 x1 x2 x3 x4 x5.(on(e1,x4) & n_skate(x4) & of(x4,x5) & n_ice(x5) & Theme(e1,x3) & Actor(e1,x1) & v_help(e1) & n_child(x3) & n_person(x1) & (x1 = x2) & ne_nam_older(x2))
exists e1 p1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_teach(e1) & Topic(x2,p1) & exists e2.(Actor(e2,x2) & v_skate(e2)) & n_person(x2) & r_more(s1) & a_older(s1) & Theme(s1,x2) & n_child(x1))