Jean-Marc Champarnaud Franck Guingne André Kempe Florent Nicart Algorithms for the Join and Auto-Intersection of Multi-Tape Weighted Finite-State Machines. 453-476 2008 19 Int. J. Found. Comput. Sci. 2 http://dx.doi.org/10.1142/S0129054108005760 db/journals/ijfcs/ijfcs19.html#ChamparnaudGKN08