A saxophonist and singer perform.
A person is playing a trumpet while someone sings along.
The instrument involved is either a saxophone (played by a saxophonist) or a trumpet, but not both.
exists e1 x1 x2 x3.(Actor(e1,x1) & v_perform(e1) & n_singer(x3) & n_saxophonist(x2) & subset_of(x3,x1) & subset_of(x2,x1))
exists e1 x1 x2 x3 x4.(while(e1,x3) & along(x3,x4) & n_sing(x4) & n_person(x3) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_trumpet(x2) & n_person(x1))