Opposing players challenge each other in a game of ultimate frisbee.
The people are playing a frisbee game.
Players are people, and and ultimate frisbee is a frisbee game.
exists e1 x1.(all x2.(n_other(x2) -> exists e2 s1 x3 x4.(in(e2,x3) & of(x3,x4) & n_frisbee(x4) & a_ultimate(s1) & Theme(s1,x4) & n_game(x3) & Theme(e2,x2) & Actor(e2,x1) & v_challenge(e2))) & n_player(x1) & Actor(e1,x1) & v_oppose(e1))
exists e1 x1 x2 x3.(n_people(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_game(x2) & of(x2,x3) & n_frisbee(x3))