A girl playing her guitar in her bedroom.
A young girl is practicing her instrument indoors.
A guitar is an instrument, so saying someone is playing her guitar can be the same as saying she is practicing her instrument.
exists e1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x4) & n_bedroom(x4) & of(x4,x1) & n_female(x1) & n_female(x1) & Theme(e1,x3) & Actor(e1,x2) & v_play(e1) & n_guitar(x3) & of(x3,x1) & (x1 = x2) & n_girl(x1))
exists e1 s1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_practice(e1) & n_indoor(x2) & of(x2,x3) & n_instrument(x3) & of(x2,x1) & n_female(x1) & n_girl(x1) & a_young(s1) & Theme(s1,x1))