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Languages with homomorphic replacements

J. Albert, L. Wegner
1981 Theoretical Computer Science  
Ahstmct, We introduce H-systems as language generators using the concept of homomorphic replace--:ent of variables by words from metalanguages.  ...  consistently each A in v by a word w E k_.+ This method of generating a language using a homomorphic type of replacement seems very natural to us and it is surprising that it has not been examine,d before  ...  Clearly L = L(((A}, {a, b), (A" 1 m z l}, cp)) with rp(A.) = {a"b 1 n 3 1) is in %'(REG, REG). Languages with homomorphic replacements 297 Assume L E %(FIN, CF).  ... 
doi:10.1016/0304-3975(81)90100-6 fatcat:z5c2jwdvjfea3oexb7rrsgpnhe

Extending regular expressions with homomorphic replacement

Henning Bordihn, Jürgen Dassow, Markus Holzer
2010 RAIRO - Theoretical Informatics and Applications  
We define H-and EH-expressions as extensions of regular expressions by adding homomorphic and iterated homomorphic replacement as new operations, resp.  ...  We compare the families of languages obtained by these extensions with the families of regular, linear context-free, context-free, and EDT0L languages.  ...  problems for expressions with homomorphic replacement.  ... 
doi:10.1051/ita/2010013 fatcat:ve6st4kopbhrdcgg3jriooad24

On some variants of the Ehrenfeucht conjecture

Volker Diekert
1986 Theoretical Computer Science  
A language is a subset of X*. It is viewed as contained in F(X), too. We use (L) to indicate the generated subgroup of a language L in F(X). By M we denote monoids.  ...  An example of such a language is the same Test sets for homomorphisms which are constant on the language The existence of test sets for homomorphisms is strongly connected with the finite presentation  ...  These languages are called languages with Hotz isomorphsm [3] . !.  ... 
doi:10.1016/0304-3975(86)90036-8 fatcat:4zsmouqcivarjgrsy33o46mrem

Idempotent tree languages

K. Denecke, N. Sarasit, S. L. Wismath
2013 Demonstratio Mathematica  
AbstractA tree language of a fixed type  ...  Our goal in this paper is to study tree languages which are idempotent with respect to a certain binary operation on sets of terms, defined by random replacement of variables.  ...  Then L is idempotent with respect to + n iff L contains at least one variable and is closed under random replacement of variables over L.  ... 
doi:10.1515/dema-2013-0425 fatcat:att4ujqrqzhfdlki3zb5cehp7a

Page 1663 of Mathematical Reviews Vol. , Issue 91C [page]

1991 Mathematical Reviews  
This paper deals with modified flowcharts which admit several sorts of vertices with several inputs and loops without exit. The free monoid is replaced by an arbitrary one.  ...  “We also prove the following result: If there exists a strong homomorphism between two languages (V,L) and (U,M), where V and U are finite sets, and if one of these languages represents a grammatized language  ... 

Page 5264 of Mathematical Reviews Vol. , Issue 98H [page]

1998 Mathematical Reviews  
The different modifications of parallel replacements are compared with each other.  ...  of languages accepted by nondeter- ministic multitape Turing-machines with a special behavior on the work tapes and running in linear time), and RE (the family of recursively enumerable languages).  ... 

On Equivalence Relations Between Interpreted Languages, with an Application to Modal and First-Order Language

Kai F. Wehmeier
2021 Erkenntnis: An International Journal of Scientific Philosophy  
structure of the underlying language.  ...  As an application, I show how to construe modal operator languages as what might be called typographical notational variants of bona fide first-order languages.  ...  Acknowledgements This paper has its origins in conversations with my late colleague and friend Aldo Antonelli about the relationship between modal and first-order language.  ... 
doi:10.1007/s10670-020-00346-w fatcat:55wzizi45jhm7dfvfgn4usosje

Page 970 of Mathematical Reviews Vol. 35, Issue 4 [page]

1968 Mathematical Reviews  
The key notion underlying the transformations dealt with is that of the ‘“permutational homomorphism”.  ...  A permutational homomorphism converts each of a set of rules into another rule by means of permutation, replace- ment, deletion, and insertion of auxiliary symbols and by means of permutation and replacement  ... 

On the decidability of homomorphism equivalence for languages

K. Culik, Arto Salomaa
1978 Journal of computer and system sciences (Print)  
Nonterminals found to be periodic and consistent with the assumption that h, and ha are equivalent on L are finally replaced by their periods, yielding the language L' of Theorem 4.2.  ...  HOMOMORPHISM EQUIVALENCE FOR CONTEXT-FREE LANGUAGES We have already settled the decidability status of our four problems for the language families in the Chomsky hierarchy, with the exception of the homomorphism  ... 
doi:10.1016/0022-0000(78)90002-8 fatcat:vg57dlei5rbfhouy7bhklipa3u

Structural aspects of local adjunct languages

Leon S. Levy
1973 Information and Control  
Also considered are some problems concerning one-sided grammars, homomorphisms of languages (it is shown that local adjunct languages are not closed under homomorphism), fl-linear languages and mixed adjunct  ...  Several open problems concerning local adjunct languages are considered and solved.  ...  The language it generates is called a simple replacement language with null symbols (SRLN). (Note: Similarly an LAGN is an MAGN whose set of replacement rules is empty.) THEOREM 7.2.  ... 
doi:10.1016/s0019-9958(73)90732-8 fatcat:cptltp6t7jhpvoo6xdinsu5nsy

On characterization of recursively enumerable languages in terms of linear languages and VW-grammars

Paavo Turakainen
1978 Indagationes Mathematicae (Proceedings)  
It is proved that for any alphabet 1: there exist a homomorphism h, a deterministic minimal linear language L 1 and a linear language L 2 such that every recursively enumerable language Lover 1: is of  ...  Some ot her homomorphic cha ra ct erizations are also presented.  ...  Since h, hI and h 2 are now acting on languages over disjoint alphabets, we may replace hI and h2 by h.  ... 
doi:10.1016/1385-7258(78)90031-8 fatcat:vookpje5a5exrl7urpnfno3wzi

Page 2218 of Mathematical Reviews Vol. 48, Issue 6 [page]

1974 Mathematical Reviews  
In other words; it is proved that L, is complete in the class of &-free cf-languages with respect to reducibility via homomorphisms.  ...  In an ordinary substitution, called by the authors “con- text-free”, a substitution rule a— Y replaces symbol a by any member of language Y under any circumstances.  ... 

Locally linear families of languages

Andries P.J. van der Walt
1976 Information and Control  
In particular, there exists a largest AFL of locally linear languages.  ...  A locally linear language is one whose words can be pumped up almost anywhere. There are striking similarities between the properties of families of locally linear languages and slip families.  ...  It is clear how one can generalize the notion of homomorphic replication to substitutive replication, viz., by replacing the homomorphisms in the definition by substitutions.Then one can proceed to prove  ... 
doi:10.1016/s0019-9958(76)90083-8 fatcat:vwyrduhgbjgvhmutxeq7jf6iqa

Analytic equivalence relations and bi-embeddability

Sy-David Friedman, Luca Motto Ros
2011 Journal of Symbolic Logic (JSL)  
apply not only to classes of countable structures defined by sentences of , but also to discrete metric or ultrametric Polish spaces, compact metrizable topological spaces and separable Banach spaces, with  ...  Luca Motto Ros Analytic equivalence relations and bi-embeddability Getting rid of the order Our main theorem remains true (in the case of embeddings) if we replace L with the language L containing just  ...  Our main theorem remains true (in the case of embeddings) if we replace L with the language L containing just one binary relational symbol (in this case we use combinatorial trees rather than ordered combinatorial  ... 
doi:10.2178/jsl/1294170999 fatcat:f7ccgxv4inbrba3tco6xc3rivu

Page 431 of Mathematical Reviews Vol. , Issue 87a [page]

1987 Mathematical Reviews  
After the declaration of the terminal markings of the abstract fragments, the sets of ter- minal marked fragments can be generated as fragment languages with the help of the given replacement rules.  ...  An analogous result was proved by Boasson with the condition Vm > 0 above replaced by Vm > 0; this led to an easier proof but a weaker result. J.-M.  ... 
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