5 research outputs found
Syntax-Directed Translations and Quasi-alphabetic Tree Bimorphisms - Revisited
Quasi-alphabetic tree bimorphisms [Steinby, Tîrn uc :
Dening syntax-directed translations by tree bimorphisms. Theor. Comput.
Sci., to appear. http://dx.doi.org/10.1016/j.tcs.2009.03.009,
2009] are reconsidered. It is known that the class of (string) translations
dened by such bimorphisms coincides with the class of syntaxdirected
translations. This result is extended to a smaller class of tree
bimorphisms namely (linear and complete) symbol-to-symbol tree bimorphisms.
Moreover, it is shown that the class of simple syntax-directed
translations coincides with the class of translations dened by alphabetic
tree bimorphisms (also known as nite-state relabelings). This proves
that alphabetic tree bimorphisms are not suciently powerful to model
all syntax-directed translations. Finally, it is shown that the class of tree
transformations dened by quasi-alphabetic tree bimorphisms is closed
under composition. The corresponding result is known in the variable-free
case