An elderly man and a young woman share a laugh on the beach.
A grandmother and her grandson laugh on the beach.
A grandmother is a woman, not a man.  A grandson is a boy, not a girl.  The elderly man can not be a grandmother,  The young woman can not be a grandson.
exists s1 s2 x1 x5.(n_beach(x5) & a_topic(s1) & all x2.(n_laugh(x2) -> exists s3 x3 x4.(subset_of(x3,s1) & on(x3,x5) & for(x3,x2) & n_share(x3) & of(x3,x4) & n_woman(x4) & a_young(s3) & Theme(s3,x3))) & subset_of(x1,s1) & n_man(x1) & a_elderly(s2) & Theme(s2,x1))
exists s1 x1 x2 x3 x4.(n_beach(x4) & a_topic(s1) & subset_of(x2,s1) & on(x2,x4) & n_laugh(x2) & of(x2,x3) & n_grandson(x3) & of(x2,x1) & n_female(x1) & subset_of(x1,s1) & n_grandmother(x1))