Several people walk up a staircase.
people climb stairs
If people are walking up a staircase, then they are climbing stairs.
exists e1 s1 s2 x1 x2.(a_up(s2) & Manner(e1,s2) & Theme(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_staircase(x2) & n_people(x1) & a_several(s1) & Theme(s1,x1))
exists x1 x2 x3.(a_topic(x1) & Time(x1,x3) & n_stair(x3) & Time(x1,x2) & n_climb(x2) & n_people(x1))