A man is riding a lawn mower on the street.
A man is riding on a lawn mower.
"riding a on a lawn mower". is a rephrasing of " riding a lawn mower".
exists e1 x1 x2 x3 x4.(n_street(x4) & on(e1,x4) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_mower(x2) & of(x2,x3) & n_lawn(x3) & n_man(x1))
exists e1 x1 x2 x3.(on(e1,x2) & n_mower(x2) & of(x2,x3) & n_lawn(x3) & Actor(e1,x1) & v_ride(e1) & n_man(x1))