A cashier at a grocery store.
a cashier is not at a grocery store
A cashier is either at a grocery store or is not at a grocery store.
exists x1 x2 x3.(a_topic(x1) & at(x1,x2) & n_store(x2) & of(x2,x3) & n_grocery(x3) & n_cashier(x1))
exists x1.(-exists p1 x2 x3.(at(x1,x2) & n_store(x2) & of(x2,x3) & n_grocery(x3)) & n_cashier(x1))