Regular solutions of language inequalities and well quasi-orders
نویسندگان
چکیده
منابع مشابه
Well - Quasi - Orders Christian
Based on Isabelle/HOL’s type class for preorders, we introduce a type class for well-quasi-orders (wqo) which is characterized by the absence of “bad” sequences (our proofs are along the lines of the proof of Nash-Williams [1], from which we also borrow terminology). Our main results are instantiations for the product type, the list type, and a type of finite trees, which (almost) directly foll...
متن کاملWell-Quasi-Orders
Based on Isabelle/HOL’s type class for preorders, we introduce a type class for well-quasi-orders (wqo) which is characterized by the absence of “bad” sequences (our proofs are along the lines of the proof of Nash-Williams [1], from which we also borrow terminology). Our main results are instantiations for the product type, the list type, and a type of finite trees, which (almost) directly foll...
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Regular languages were characterized as sets closed with respect to monotone well-quasi orders. A similar result is proved here for tree languages. Moreover, families of quasi orders that correspond to positive varieties of tree languages and varieties of finite ordered algebras are characterized.
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The purpose of this article is to study the role of Gödel’s functional interpretation in the extraction of programs fromproofs inwell quasi-order theory. Themain focus is on the interpretation of Nash-Williams’ famous minimal bad sequence construction, and the exploration of a number of much broader problems which are related to this, particularly the question of the constructive meaning of Zor...
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The paper investigates down-sets associated to well quasi orders. Of particular language-theoretic interest is the quasi order u s v (resp.u P v) of u being a subword (resp. a Parikh subword) of v, as well as their inverses. We establish a number of results about the regularity and e ective regularity of the down-sets, in particular, a general condition for the e ective regularity of the down-s...
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2005
ISSN: 0304-3975
DOI: 10.1016/j.tcs.2005.09.018