A man is lead singer in a band at an outdoor venue.
A man is a backup singer
A backup singer is different than a lead singer.
exists p1 s1 x1 x2 x3.(in(p1,x2) & at(x2,x3) & n_venue(x3) & a_outdoor(s1) & Theme(s1,x3) & n_band(x2) & exists s2 x4.((x1 = x4) & n_singer(x4) & a_lead(s2) & Theme(s2,x4)) & n_man(x1))
exists p1 x1.(exists x2 x3.((x1 = x2) & n_singer(x2) & of(x2,x3) & n_backup(x3)) & n_man(x1))