A person in a red jacket singing while playing the electric guitar.
The rock star sings his latest song at the concert.
The person performing may be an amateur and not a rock star. The song the person is singing may not be his latest song but one someone else wrote. Just because the person is playing an electric guitar doesn't mean he is at concert.
exists e1 e2 s1 s2 x1 x2 x3 x4.(n_guitar(x4) & a_electric(s2) & Theme(s2,x4) & a_topic(x1) & in(x1,x2) & while(e1,e2) & Theme(e2,x4) & Actor(e2,x3) & v_play(e2) & Actor(e1,x3) & v_sing(e1) & (x2 = x3) & n_jacket(x2) & a_red(s1) & Theme(s1,x2) & n_person(x1))
exists e1 s1 x1 x2 x3 x4.(n_concert(x4) & n_song(x3) & r_most(s1) & a_latest(s1) & Theme(s1,x3) & of(x3,x1) & n_male(x1) & n_star(x1) & of(x1,x2) & n_rock(x2) & at(e1,x4) & Theme(e1,x3) & Actor(e1,x1) & v_sing(e1))