A class of rational n-WFSM auto-intersections

Abstract. Weighted finite-state machines with n tapes describe n-ary rational string relations. The join n-ary relation is very important regarding to applications. It is shown how to compute it via a more simple operation, the auto-intersection. Join and auto-intersection generally do not preserve rationality. We define a class of triples 〈A,i, j 〉 such that the auto-intersection of the machine A w.r.t. tapes i and j can be computed by a delay-based algorithm. We point out how to extend this class and hope that it is sufficient for many practical applications.