There is a crowd of people at an outdoor station including some men in hard hats and safety jackets.
The hard hats are necessary.
Hard hats are not always necessary.
exists p1 x1 s1 s2 x2 x3 x4 x5 x6 x7 x8 x9.((x1 = x2) & include(x2,x5) & subset_of(x8,x5) & n_jacket(x8) & of(x8,x9) & n_safety(x9) & subset_of(x6,x5) & in(x6,x7) & n_hat(x7) & a_hard(s2) & Theme(s2,x7) & n_man(x6) & at(x2,x4) & n_station(x4) & a_outdoor(s1) & Theme(s1,x4) & of(x2,x3) & n_people(x3) & n_crowd(x2))
exists s1 s2 x1.(n_hat(x1) & a_hard(s1) & Theme(s1,x1) & Theme(s2,x1) & a_necessary(s2))