The security guard is smiling.
There is a security guard that is smiling.
Both subjects are smiling
exists e1 x1 x2.(n_guard(x1) & of(x1,x2) & n_security(x2) & Actor(e1,x1) & v_smile(e1))
exists p1 x1 e1 x2 x3 x4.((x1 = x2) & Actor(e1,x4) & v_smile(e1) & (x2 = x4) & n_guard(x2) & of(x2,x3) & n_security(x3))