A runner is leaping over hurdles.
the runner is walking
They can't be walking and leaping.
exists e1 x1 x2.(over(e1,x2) & n_hurdle(x2) & Actor(e1,x1) & v_leap(e1) & n_runner(x1))
exists e1 x1.(n_runner(x1) & Actor(e1,x1) & v_walk(e1))