Compositions of Weighted Extended Tree Transducers — The Unambiguous Case

Abstract

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 [Formula: see text] with a nondeleting weighted top-down tree transducer [Formula: see text] 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 [Formula: see text] (even if it is not nondeleting) if the unambiguous weighted extended tree transducer [Formula: see text] is constant.