کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
429983 | 687761 | 2015 | 26 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
MIX is a 2-MCFL and the word problem in Z2Z2 is captured by the IO and the OI hierarchies
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی کامپیوتر
نظریه محاسباتی و ریاضیات
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: MIX is a 2-MCFL and the word problem in Z2Z2 is captured by the IO and the OI hierarchies MIX is a 2-MCFL and the word problem in Z2Z2 is captured by the IO and the OI hierarchies](/preview/png/429983.png)
چکیده انگلیسی
In this work we establish that the language MIX={w∈{a;b;c}⁎||w|a=|w|b=|w|c}MIX={w∈{a;b;c}⁎||w|a=|w|b=|w|c} and the language O2={w∈{a;a¯;b;b¯}||w|a=|w|a¯∧|w|b=|w|b¯} are 2-MCFLs. As 2-MCFLs form a class of languages that is included in both the IO and OI hierarchies, and as O2O2 is the group language of a simple presentation of Z2Z2 we exhibit here the first, to our knowledge, non-virtually-free group language (i.e. non-context-free group language) that is captured by the IO and OI hierarchies. Moreover, it was a long-standing open problem whether MIX was a mildly context sensitive language or not, and it was conjectured that it was not, so we close this conjecture by giving it a negative answer.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Computer and System Sciences - Volume 81, Issue 7, November 2015, Pages 1252–1277
Journal: Journal of Computer and System Sciences - Volume 81, Issue 7, November 2015, Pages 1252–1277
نویسندگان
Sylvain Salvati,