People at a kickboxing class.
The friends are kickboxing.
Just because people are kickboxing at a class that does not mean they are friends.
exists e1 x1 x2.(a_topic(x1) & at(x1,x2) & n_class(x2) & Actor(e1,x2) & v_kickbox(e1) & n_people(x1))
exists e1 x1.(n_friend(x1) & Actor(e1,x1) & v_kickbox(e1))