A man is investigating an internal problem within his tractor.
There is a cow that is headbutting a tractor.
The man cannot also be a cow
exists e1 s1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_investigate(e1) & within(x2,x3) & n_tractor(x3) & of(x3,x1) & n_male(x1) & n_problem(x2) & a_internal(s1) & Theme(s1,x2) & n_man(x1))
exists p1 x1 e1 x2 x3 x4.((x1 = x2) & Theme(e1,x4) & Actor(e1,x3) & v_headbut(e1) & n_tractor(x4) & (x2 = x3) & n_cow(x2))