This memorial is to remember victims of a tragedy.
A memorial for the 9/11 terrorist attacks.
The memorial might be for something besides the 9/11 attacks.
exists e1 p1 x1.(n_memorial(x1) & Topic(e1,p1) & Actor(e1,x1) & v_be(e1) & exists e2 x2 x3.(Theme(e2,x2) & Actor(e2,x1) & v_remember(e2) & of(x2,x3) & n_tragedy(x3) & n_victim(x2)))
exists s1 s2 x1 x2.(n_attack(x2) & a_terrorist(s2) & Theme(s2,x2) & a_9/11(s1) & Theme(s1,x2) & a_topic(x1) & for(x1,x2) & n_memorial(x1))