People sit on benches.
People are standing around talking.
People can not be both sitting and standing.
exists e1 x1 x2.(on(e1,x2) & n_bench(x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1))
exists e1 e2 x1.(around(e1,e2) & Actor(e2,x1) & v_talk(e2) & Actor(e1,x1) & v_stand(e1) & n_people(x1))