A bassist and a guitarist are performing at a concert.
Two people are playing instruments.
A bassist and a guitarist equal two people. Someone performing at a concert would be playing instruments.
exists e1 x1 x2 x3 x4.(at(e1,x4) & n_concert(x4) & Actor(e1,x1) & v_perform(e1) & subset_of(x3,x1) & n_guitarist(x3) & subset_of(x2,x1) & n_bassist(x2))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_instrument(x2) & n_people(x1) & card_eq_2(x1))