A man and woman kiss on a train.
A man and woman kissing.
Kiss and kissing are same activity
exists s1 x1 x2 x3 x4.(a_topic(s1) & subset_of(x2,s1) & on(x2,x4) & n_train(x4) & n_kiss(x2) & of(x2,x3) & n_woman(x3) & subset_of(x1,s1) & n_man(x1))
exists s1 x1 x2 x3.(a_topic(s1) & subset_of(x2,s1) & n_kissing(x2) & of(x2,x3) & n_woman(x3) & subset_of(x1,s1) & n_man(x1))