A Quadratic Upper Bound on the Size of a Synchronizing Word in One-Cluster Automata.

Marie-Pierre Béal Dominique Perrin A Quadratic Upper Bound on the Size of a Synchronizing Word in One-Cluster Automata. 81-90 2009 Developments in Language Theory http://dx.doi.org/10.1007/978-3-642-02737-6_6 conf/dlt/2009 db/conf/dlt/dlt2009.html#BealP09