Compositions of Weighted Extended Tree Transducers - The Unambiguous Case

Generalizations of another two open conjectures, Conjectures 13 and 14, of [Lagoutte, Maletti: Survey - Weighted extended top-down tree transducers - Part III: Composition. Proc. AFCS, LNCS 7020, p. 272-308, Springer 2011] are verified. It is proved that the composition of an unambiguous weighted extended tree transducer M with a nondeleting weighted top-down tree transducer N can be computed by a single weighted extended tree transducer. Extending the recent confirmation of Conjecture 11 it is also proved that the composition succeeds for any weighted top-down tree transducer N (even if it is not nondeleting) if the unambiguous weighted extended tree transducer M is constant.