Running times of sequence-structure alignment programs. The plot shows a comparison of the running times between the structural programs tested. With an increasing number of input sequences, a progressive alignment strategy pays off compared to the computation of all pairwise alignments. The x-axis lists the different input instances, either containing 2, 3, 5, 7, 10, or 15 sequences (denoted by k 2, k 3, k 5, k 7, k 10, and k 15, respetively). The numbers in brackets denote the number of instances per input class. The y-axis gives the number gives the computation time in seconds.