Several Aspects of Context Freeness for Hyperedge Replacement Grammars
نویسنده
چکیده
In this paper we survey several aspects related to normal forms of hyperedge replacement grammars. Considering context free hyperedge replacement grammars we introduce, inspired by string grammars, Chomsky Normal Form and Greibach Normal Form. The algorithm of conversion is quite the same with the algorithm for string grammars. The important difference is related to the fact that hyperedge grammars are two-dimensional and that’s why parsing productions, in order to transform into string grammars, can be done only nondeterministic. A detailed example of conversion to both normal forms is introduced to clarify all the algorithm steps. Key-Words: Hyperedge Replacement Grammars, Normal Form, Chomsky, Greibach, Context Freeness, Nondeterministic
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