We prove that for a given deterministic top-down transducer with look-ahead it is decidable whether or not its translation is definable (1)~by a linear top-down tree transducer or (2)~by a tree homomorphism. We present algorithms that construct equivalent such transducers if they exist.

中文翻译：

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自上而下的树转换器的可定义性结果

我们证明，对于给定的具有前瞻的确定性自顶向下转换器，它的平移是否可定义（1）~由线性自顶向下树转换器或（2）~由树同态定义。我们提出了构建等效的此类传感器（如果存在）的算法。