Special Issue on Selected Papers from the 11th International Conference and Workshops on Algorithms and Computation, WALCOM 2017 Sequentially Swapping Colored Tokens on Graphs Vol. 23, no. 1, pp. 3-27, 2019. Regular paper. Abstract We consider a puzzle consisting of colored tokens on an $n$-vertex graph, where each token has a distinct starting vertex and a set of allowable target vertices for it to reach, and the only allowed transformation is to "sequentially" move the chosen token along a path of the graph by swapping it with other tokens on the path. Submitted: September 2017. Reviewed: May 2018. Revised: June 2018. Reviewed: October 2018. Revised: October 2018. Accepted: October 2018. Final: November 2018. Published: January 2019. Communicated by Md. Saidur Rahman, Hsu-Chun Yen, and Sheung-Hung Poon article (PDF) BibTeX