A boy in a dark shirt is reading a book while sitting on a piano bench.
The boy is on a piano bench.
A boy sitting on a piano bench is a rephrasing of the boy is on a piano bench.
exists e2 e1 s1 x1 x2 x3 x4 x5.(while(e1,e2) & on(e2,x4) & n_bench(x4) & of(x4,x5) & n_piano(x5) & Actor(e2,x1) & v_sit(e2) & Theme(e1,x3) & Actor(e1,x1) & v_read(e1) & n_book(x3) & in(x1,x2) & n_shirt(x2) & a_dark(s1) & Theme(s1,x2) & n_boy(x1))
exists p1 x1.(n_boy(x1) & exists x2 x3.(on(x1,x2) & n_bench(x2) & of(x2,x3) & n_piano(x3)))