A singer performs with his band mates who are playing guitar and keyboards.
the band is preforming
A singer and his band mates can be shortened to simply a band performing.
exists e1 e2 x1 x2 x3 x4 x5 x6 x7.(with(e1,x2) & Theme(e2,x5) & Actor(e2,x4) & v_play(e2) & subset_of(x7,x5) & n_keyboard(x7) & subset_of(x6,x5) & n_guitar(x6) & (x2 = x4) & n_mate(x2) & of(x2,x3) & n_band(x3) & of(x2,x1) & n_male(x1) & Actor(e1,x1) & v_perform(e1) & n_singer(x1))
exists e1 x1.(n_band(x1) & Actor(e1,x1) & v_preform(e1))