A guitar player sings on a stage.
The guitarist is in the studio.
A guitar player sings on a stage and other one  is in the studio.
exists x1 x2 x3 x4.(a_topic(x1) & on(x1,x4) & n_stage(x4) & n_sing(x1) & of(x1,x3) & n_player(x3) & of(x1,x2) & n_guitar(x2))
exists p1 x1 x2.(n_studio(x2) & n_guitarist(x1) & in(x1,x2))