Marked length rigidity for one dimensional spaces

Any two compact, complete, one-dimensional geodesic spaces with identical marked length spectrum have isometric ${\pi }_1$-hull. The present version contains errors, notably in Lemmas 2.2 and 2.3 (path cancellations can be more complicated), which then propagate through the paper. The main result is correct as stated, and a proof can be found in the joint paper with David Constantine, arXiv:1209.3709