People ride up an escalator.
They are at the mall
Many different types of buildings have escalators, the people do not have to be at a mall.
exists e1 s1 x1 x2.(a_up(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_escalator(x2) & n_people(x1))
exists p1 x1 x2.(n_mall(x2) & n_thing(x1) & at(x1,x2))