Fig. 18

(i) The same concatenated unsaturated path-line can intersect with several balanced links (double-lines and/or cycle-lines). The optimal (yellow) solution is found by first selecting the paths with odd numbers in the unsaturated path-line and then, for each balanced link, selecting the compatible set of vertices among the two alternating choices. (ii) If the unsaturated path-line is cyclic and has odd length, the last path must be excluded from the optimal solution