词语言上的良拟序
Well-Quasi-Orderings on Word Languages
AI总结:
本文研究词上前缀、后缀、中缀等自然序下的类Higman定理,刻画了对应良拟序词语言的特征,并为一大类语言提供了判定过程。
摘要:
良拟序集合上的有限词集合本身也是良拟序的。Higman的这一开创性成果是良拟序理论的基石,在计算机科学中已有众多应用。但该结果基于词上的一种特定序选择,即(分散)子词序。本文中,我们阐述了词上其他自然序(前缀序、后缀序和中缀序)可在多大程度上用于推导类Higman定理。更具体地说,我们关注刻画在这些序下为良拟序的词语言。我们证明前缀序和后缀序存在简单刻画,且在额外的正则性假设下,该结论也可扩展到中缀序。我们还为包含正则语言和上下文无关语言在内的一大类语言提供了判定过程。
英文摘要:
The set of finite words over a well-quasi-ordered set is itself well-quasi-ordered. This seminal result by Higman is a cornerstone of the theory of well-quasi-orderings and has found numerous applications in computer science. However, this result is based on a specific choice of ordering on words, the (scattered) subword ordering. In this paper, we describe to what extent other natural orderings (prefix, suffix, and infix) on words can be used to derive Higman-like theorems. More specifically, we are interested in characterizing languages of words that are well-quasi-ordered under these orderings. We show that a simple characterization is possible for the prefix and suffix orderings, and that under extra regularity assumptions, this also extends to the infix ordering. We furthermore provide decision procedures for a large class of languages, that contains regular and context-free languages.
机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。