Two people walk outside in a nature area.
Two people hike as part of a fundraiser event.
Hike is different than walk.  Nothing mentioned it's a fundraiser.
exists e1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x4) & n_nature(x4) & outside(e1,x3) & n_area(x3) & Theme(e1,x2) & v_walk(e1) & (x1 = x2) & n_people(x1) & card_eq_2(x1))
exists s1 x1 x2 x3 x4 x5.(a_topic(x1) & as(s1,x3) & of(x3,x4) & n_event(x4) & of(x4,x5) & n_fundraiser(x5) & n_part(x3) & Theme(s1,x2) & a_hike(s1) & (x1 = x2) & n_people(x1) & card_eq_2(x1))