A dissimilarity D on a finite set S is said to be Robinsonian if S can be totally ordered in such a way that, for every i j k, D (i, j) ≤ D (i, k) and D (j, k) ≤ D (i, k). Intuitively, D is Robinsonian if S can be represented by points on a line. Recognizing Robinsonian dissimilarities has...