A man in a hat is playing an acoustic guitar with a band at an outdoor venue.
A man in a hat is playing a guitar in a band.
" a man is playing a/an guitar" is the same meaning and wording as " a man is playing a/an guitar".
exists e1 s1 s2 x1 x2 x3 x4 x5.(with(e1,x4) & at(x4,x5) & n_venue(x5) & a_outdoor(s2) & Theme(s2,x5) & n_band(x4) & Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & n_guitar(x3) & a_acoustic(s1) & Theme(s1,x3) & in(x1,x2) & n_hat(x2) & n_man(x1))
exists e1 x1 x2 x3 x4.(in(e1,x4) & n_band(x4) & Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & n_guitar(x3) & in(x1,x2) & n_hat(x2) & n_man(x1))