In addition, different form that in topic segmentation, where a segment must not be empty, we shall allow a bullet b i to be aligned to an empty region, to model the situation that a bullet is not discussed by the speaker.
to do so, we made j in equation 2and (3) above to be able to equal to k in the subscript, i.e., j ≤ k. when j = k, the set A i,j+1,k has no internal edges, and D[i, j + 1, k] is either equal to 1, or often not defined if assoc(A i,j+1,k , V ) = 0.