A person in a green shirt skateboards.
A person in a red shirt rollerblades
Skateboards and rollerblades must be done by two different people, especially if they are wearing different colors
exists s1 x1 x2 x3.(a_topic(x1) & in(x1,x2) & n_skateboard(x2) & of(x2,x3) & n_shirt(x3) & a_green(s1) & Theme(s1,x2) & n_person(x1))
exists s1 x1 x2 x3.(a_topic(x1) & in(x1,x2) & n_rollerblade(x2) & of(x2,x3) & n_shirt(x3) & a_red(s1) & Theme(s1,x2) & n_person(x1))