A musician sitting at his piano.
A man sitting next to a piano
A man who is a musician of whom sitting at his piano is the same as sitting next to a piano.
exists e1 x1 x2 x3.(a_topic(x1) & at(e1,x3) & n_piano(x3) & of(x3,x1) & n_male(x1) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_musician(x1))
exists e1 x1 x2 x3.(a_topic(x1) & to(e1,x3) & n_piano(x3) & r_next(e1) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_man(x1))