The men are climbing.
The men are rock climbing.
Just because men are climbing does not mean they are rock climbing.
exists e1 x1.(n_man(x1) & Actor(e1,x1) & v_climb(e1))
exists e1 x1 x2.(n_man(x1) & Time(e1,x2) & n_rock(x2) & Actor(e1,x1) & v_climb(e1))