Nonterminal complexity of tree controlled grammars
نویسندگان
چکیده
This paper studies the nonterminal complexity of tree controlled grammars. It is proved that the number of nonterminals in tree controlled grammars without erasing rules leads to an infinite hierarchy of families of tree controlled languages, while every recursively enumerable language can be generated by a tree controlled grammar with erasing rules and at most nine nonterminals. © 2011 Elsevier B.V. All rights reserved.
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ورودعنوان ژورنال:
- Theor. Comput. Sci.
دوره 412 شماره
صفحات -
تاریخ انتشار 2011