Results 11 to 20 of about 4,373 (234)
A homomorphic characterization of recursively enumerable languages
Theoretical Computer Science, 1985 We give a homomorphic characterization of the class of recursively enumerable languages: it is shown that any recursively enumerable language is the homomorphic image of the intersection of a Dyck language and a 'minimal linear' language.
Sadaki Hirose +2 more
openaire +3 more sources
Representing recursively enumerable languages by iterated deletion
Theoretical Computer Science, 2004 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Michael Domaratzki, Alexander Okhotin
openaire +4 more sources
Fixed Point Languages, Equality Languages, and Representation of Recursively Enumerable Languages [PDF]
Journal of the ACM, 1980 Fixed point languages and equality languages of homomorphisms and dgsm mappings are consid- ered. Some basic properties of these classes of languages are proved, and it is shown how to use them to represent recursively enumerable sets. In particular, very simple languages are introduced which play the same role for the class of recursively enumerable ...
Engelfriet, J., Rozenberg, G.
openaire +3 more sources
On representing recursively enumerable languages by internal contextual languages
Theoretical Computer Science, 1998 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Andrzej Ehrenfeucht +2 more
openaire +3 more sources
Information and Control, 1980 A method of encoding the computation histories of a wide class of machines is introduced and used to derive several representation theorems for the class of recursively enumerable languages. In particular it is demonstrated that any recursively enumerable language K ⊂ Σ* can be represented as K = ΦΣ(R ∩ D1 ⋮ D2), where D1 and D2 are fixed semi-Dyck ...
David Haussler, H. Paul Zeiger
openaire +3 more sources
A representation of recursively enumerable languages by two homomorphisms and a quotient
Theoretical Computer Science, 1988 For two strings x and y, \(x\setminus y\) is the string z when \(y=xz\); otherwise \(x\setminus y\) is undefined. The author proves the following representation theorem: For each recursively enumerable set L (over alphabet \(\Sigma)\) there exist two homomorphisms \(h_ 1\), \(h_ 2:\) \(\Sigma^*_ 1\to \Sigma^*_ 2\) \((\Sigma \subseteq \Sigma_ 2)\) such ...
Viliam Geffert
openaire +3 more sources
Homomorphic characterizations of recursively enumerable languages with very small language classes
Theoretical Computer Science, 2001 In this paper, we attempt to characterize the class of recursively enumerable languages with much smaller language classes than that of linear languages. Language classes, \((i,j)\) LL and \((i,j)ML,\) of \((i,j)\) linear languages and \((i,j)\) minimal linear languages are defined by posing restrictions on the form of production rules and the number ...
Satoshi Okawa, Sadaki Hirose
openaire +3 more sources
Membrane division, restricted membrane creation and object complexity in P systems [PDF]
, 2006 We improve, by using register machines, some existing universality results for specific models of P systems. P systems with membrane creation are known to generate all recursively enumerable sets of vectors of non-negative integers, even when no region
Alhazov, Artiom +2 more
core +1 more source
On the Complexity of Limit Sets of Cellular Automata Associated with Probability Measures [PDF]
, 2006 We study the notion of limit sets of cellular automata associated with probability measures (mu-limit sets). This notion was introduced by P. Kurka and A. Maass. It is a refinement of the classical notion of omega-limit sets dealing with the typical long
J. Kari +6 more
core +6 more sources
The omega-inequality problem for concatenation hierarchies of star-free languages [PDF]
, 2017 The problem considered in this paper is whether an inequality of omega-terms is valid in a given level of a concatenation hierarchy of star-free languages.
Almeida, J., Klíma, O., Kunc, M.
core +2 more sources