Ogden's Lemma for Regular Tree Languages

We motivate and prove a strong pumping lemma for regular tree languages. The new lemma can be seen as the natural correspondent of Ogden's lemma for context-free string languages.

[1]  Joost Engelfriet,et al.  Output String Languages of Compositions of Deterministic Macro Tree Transducers , 2002, J. Comput. Syst. Sci..

[2]  William F. Ogden,et al.  A helpful result for proving inherent ambiguity , 1968, Mathematical systems theory.

[3]  Ferenc Gécseg,et al.  Tree Languages , 1997, Handbook of Formal Languages.