Supplement to: ‘Boundary stabilization of hyperbolic systems related to overhead cranes’ [H. Sano, IMA J. Math. Control Inf. (2008) vol. 25, 353–366, doi:10.1093/imamci/dnm031]

In the paper cited in the heading, we treated the problem of stabilizing a flexible cable with two rigid loads, which was described by two kinds of hyperbolic equations. To show the asymptotic stability of the closed-loop system with a controller derived there, we used the LaSalle's invariance principle. However, in that paper, we need to supplement the proof of Theorem 5.1 and to revise the proof of Theorem 5.2. Throughout this note, we use the same notation as in the paper cited in the heading.