Top-down Deterministic Languages
نویسنده
چکیده
Two new families of languages, the F(k) and U(k) languages, are Introduced each of which is, in some sense, a generalization of top-down deterministic languages. This leads us to new characterizations of s-grammars and LL(1) languages. We include a characterization of the unambiguous context-free languages, generalizations of the equivalence relation on s-grammars to LL(k) grammars, and a summary of the non-closure results for LL(k), F(k) and U(k) languages, and it is shown that non-degenerate hierarchies exist for the families of F(k) and U(k) languages.
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