A man sitting at a piano singing.
A man playing in front of a big crowd.
Just because a man sings at a piano does not mean that he is playing in front of a big crowd.
exists e1 x1 x2 x3 x4.(a_topic(x1) & at(e1,x3) & n_singing(x3) & of(x3,x4) & n_piano(x4) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_man(x1))
exists e1 s1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x3) & of(x3,x4) & n_crowd(x4) & a_big(s1) & Theme(s1,x4) & n_front(x3) & Actor(e1,x2) & v_play(e1) & (x1 = x2) & n_man(x1))