On Shuffling a Word with its Letter-to-Letter Substitution

Author(s):  
Vesa Halava ◽  
Tero Harju ◽  
Esa Sahla
Keyword(s):  

Denote by ⧢ the operation of interleaving, or shuffling, of words. We prove that, given a regular language R and a letter-to-letter morphism ϕ, it is undecidable whether or not there exists a word w such that w ⧢ ϕ(w) ∩ R ≠ ∅.

2011 ◽  
Vol 18 (5) ◽  
pp. 771-781 ◽  
Author(s):  
Gregory Kucherov ◽  
Tamar Pinhas ◽  
Michal Ziv-Ukelson

2010 ◽  
Author(s):  
K. M. Ravi ◽  
Alka Choubey ◽  
R. B. Patel ◽  
B. P. Singh

2017 ◽  
Vol 101 ◽  
pp. 132-140 ◽  
Author(s):  
Jordi A. Matías-Guiu ◽  
Fernando Cuetos ◽  
María Nieves Cabrera-Martín ◽  
María Valles-Salgado ◽  
Teresa Moreno-Ramos ◽  
...  

Author(s):  
Stefano Crespi Reghizzi ◽  
Luca Breveglieri ◽  
Angelo Morzenti

Author(s):  
Anastasiia Ruda

The relevance of the chosen topic can be explained by the rapid expansion of the international relations of Ukraine with other states, the trends towards the country’s integration into educational and scientific European and world spaces. This fact leads to an increase in the volume of business documents in this area and determines the search for the optimal rendering all substantive and formal parameters of the Ukrainian business documents into English, the language of international communication. The aim of the study is to identify the specifics of the translation of the modern Ukrainian business documents into English. The results of the study prove grammatical translation transformations to be the most frequent ones, which make up 90 % of all stated translation techniques. Replacements of the parts of speech are quite common within the framework of the material under study, which make up 35 %. Replacement of the parts of speech in most cases causes another type of replacement, namely, replacement of the parts of the sentence, which makes 30 % of the cases (syntactic restructuring). The second place is occupied by transposition (10 %). The least frequent transformations in the translation of the texts of the Ukrainian invitations into English are syntactic assimilation (literal translation), sentences merging and splitting (5 % each). Lexical translation transformations also make up an insignificant part (10 %) of the total number of the specified transformations. The linguistic manifestation of the translation of the studied type of the text is focused primarily on the target language, since it is important to render the informative content in the regular language form.


Author(s):  
Jürgen Dassow

For a regular language [Formula: see text], let [Formula: see text] be the minimal number of nonterminals necessary to generate [Formula: see text] by right linear grammars. Moreover, for natural numbers [Formula: see text] and an [Formula: see text]-ary regularity preserving operation [Formula: see text], let the range [Formula: see text] be the set of all numbers [Formula: see text] such that there are regular languages [Formula: see text] with [Formula: see text] for [Formula: see text] and [Formula: see text]. We show that, for the circular shift operation [Formula: see text], [Formula: see text] is infinite for all [Formula: see text], and we completely determine the set [Formula: see text]. Moreover, we give a precise range for the left right quotient and a partial result for the left quotient. Furthermore, we add some values to the range for the operation intersection which improves the result of [2].


2017 ◽  
Vol 6 (1) ◽  
pp. 36-55 ◽  
Author(s):  
Kanchan Tyagi ◽  
Alka Tripathi

Automata theory plays a key role in computational theory as many computational problems can be solved with its help. Formal grammar is a special type of automata designed for linguistic purposes. Formal grammar generates formal languages. Rough grammar and rough languages were introduced to incorporate the imprecision of real languages in formal languages. These languages have limitations on uncertainty. The authors have considered both uncertainty and approximations to define rough fuzzy grammar and rough fuzzy languages. Under certain restrictions, their grammar reduces to formal grammar. Furthermore, the authors have proposed definition of rough fuzzy automata that accepts rough fuzzy regular language.


2011 ◽  
Vol 22 (08) ◽  
pp. 1813-1828 ◽  
Author(s):  
VOLKER DIEKERT ◽  
STEFFEN KOPECKI

The hairpin completion is an operation on formal languages which is inspired by the hairpin formation in biochemistry. Hairpin formations occur naturally within DNA-computing. It has been known that the hairpin completion of a regular language is linear context-free, but not regular, in general. However, for some time it is was open whether the regularity of the hairpin completion of a regular language is decidable. In 2009 this decidability problem has been solved positively in [5] by providing a polynomial time algorithm. In this paper we improve the complexity bound by showing that the decision problem is actually NL-complete. This complexity bound holds for both, the one-sided and the two-sided hairpin completions.


2010 ◽  
Vol 21 (05) ◽  
pp. 843-858 ◽  
Author(s):  
ANDREAS MALCHER ◽  
CARLO MEREGHETTI ◽  
BEATRICE PALANO

Iterative arrays (IAs) are a parallel computational model with a sequential processing of the input. They are one-dimensional arrays of interacting identical deterministic finite automata. In this paper, realtime-IAs with sublinear space bounds are used to recognize formal languages. The existence of an infinite proper hierarchy of space complexity classes between logarithmic and linear space bounds is proved. Some decidability questions on logarithmically space bounded realtime-IAs are investigated, and an optimal logarithmic space lower bound for non-regular language recognition on realtime-IAs is shown. Finally, some non-recursive trade-offs between space bounded realtime-IAs are emphasized.


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