Filters








881 Hits in 3.3 sec

The unambiguity of segmented morphisms

Dominik D. Freydenberger, Daniel Reidenbach
2009 Discrete Applied Mathematics  
Furthermore, it shows that, among the widely used homogeneous morphisms, most segmented morphisms are optimal in terms of being unambiguous for a preferably large set of strings.  ...  Motivated by the recent initial paper on the ambiguity of morphisms, we introduce the definition of a so-called segmented morphism σ n , which, for any n ∈ N, maps every symbol in an infinite alphabet  ...  Furthermore, we thank the referees of the conference version [5] of this paper for their helpful remarks.  ... 
doi:10.1016/j.dam.2009.06.009 fatcat:nnqq3hmuuvaf5hmtktu3sadf6u

The Unambiguity of Segmented Morphisms [chapter]

Dominik D. Freydenberger, Daniel Reidenbach
Lecture Notes in Computer Science  
In the present paper, we examine the impact of n on the unambiguity of σn with respect to any α ∈ ∆ + , i. e. the question of whether there does not exist a morphism τ satisfying τ (α) = σn(α) and, for  ...  A segmented morphism σn : ∆ * −→ {a, b} * , n ∈ N, maps each symbol in ∆ onto a word which consists of n distinct subwords in ab + a.  ...  the unambiguity of morphisms.  ... 
doi:10.1007/978-3-540-73208-2_19 fatcat:stk55fbkjbgnvb64d4h77usj2e

Restricted ambiguity of erasing morphisms

Daniel Reidenbach, Johannes C. Schneider
2011 Theoretical Computer Science  
Furthermore, we demonstrate that there are strings for which the set of unambiguous morphisms, depending on the size of the target alphabet of these morphisms, is empty, finite or infinite.  ...  Finally, we show that the problem of the existence of unambiguous erasing morphisms is equivalent to some basic decision problems for nonerasing multi-pattern languages. (Johannes C.  ...  As pointed out by Schneider [14] , here the existence of an unambiguous erasing morphism does not only depend on the structure of the string, but also on the size of the target alphabet of the morphism  ... 
doi:10.1016/j.tcs.2011.02.041 fatcat:g6x3l6vifbdbrb465rtf3ajqfa

Restricted Ambiguity of Erasing Morphisms [chapter]

Daniel Reidenbach, Johannes C. Schneider
2010 Lecture Notes in Computer Science  
Furthermore, we demonstrate that there are strings for which the set of unambiguous morphisms, depending on the size of the target alphabet of these morphisms, is empty, finite or infinite.  ...  Finally, we show that the problem of the existence of unambiguous erasing morphisms is equivalent to some basic decision problems for nonerasing multi-pattern languages. (Johannes C.  ...  As pointed out by Schneider [14] , here the existence of an unambiguous erasing morphism does not only depend on the structure of the string, but also on the size of the target alphabet of the morphism  ... 
doi:10.1007/978-3-642-14455-4_35 fatcat:k27whae5qbg3fiyrnfs753cwfe

UNAMBIGUOUS MORPHIC IMAGES OF STRINGS

DOMINIK D. FREYDENBERGER, DANIEL REIDENBACH, JOHANNES C. SCHNEIDER
2006 International Journal of Foundations of Computer Science  
Motivated by the research on pattern languages, we study a fundamental combinatorial question on morphisms in free semigroups: With regard to any string α over some alphabet we ask for the existence of  ...  a morphism σ such that σ(α) is unambiguous, i.e. there is no morphism ρ with ρ = σ and ρ(α) = σ(α).  ...  The authors are indebted to Frank Hechler and the referees for numerous useful comments and, in particular, for pointing out the analogy between prolix patterns and fixed points of morphisms.  ... 
doi:10.1142/s0129054106004017 fatcat:ae2d7aszqbeshjk37emjjuji3q

Unambiguous Morphic Images of Strings [chapter]

Dominik D. Freydenberger, Daniel Reidenbach, Johannes C. Schneider
2005 Lecture Notes in Computer Science  
Motivated by the research on pattern languages, we study a fundamental combinatorial question on morphisms in free semigroups: With regard to any string α over some alphabet we ask for the existence of  ...  a morphism σ such that σ(α) is unambiguous, i.e. there is no morphism ρ with ρ = σ and ρ(α) = σ(α).  ...  The authors are indebted to Frank Hechler and the referees for numerous useful comments and, in particular, for pointing out the analogy between prolix patterns and fixed points of morphisms.  ... 
doi:10.1007/11505877_22 fatcat:duk2dpzdtzdqpdtcpsz2hjvbi4

Unambiguous Erasing Morphisms in Free Monoids [chapter]

Johannes C. Schneider
2009 Lecture Notes in Computer Science  
target alphabet of the morphism.  ...  The present paper demonstrates that, in contrast to the main result by Freydenberger et al., the existence of an unambiguous erasing morphism for a given string can essentially depend on the size of the  ...  Introduction The examination of the unambiguity of morphisms arises from the research on pattern languages.  ... 
doi:10.1007/978-3-540-95891-8_43 fatcat:tyszwwitffhkph6efph4tsr4zy

Unambiguous erasing morphisms in free monoids

Johannes C. Schneider
2009 RAIRO - Theoretical Informatics and Applications  
target alphabet of the morphism.  ...  The present paper demonstrates that, in contrast to the main result by Freydenberger et al., the existence of an unambiguous erasing morphism for a given string can essentially depend on the size of the  ...  Introduction The examination of the unambiguity of morphisms arises from the research on pattern languages.  ... 
doi:10.1051/ita/2009020 fatcat:wc2rzy23ofcp3cty4gmfkt6egi

Unambiguous 1-Uniform Morphisms

Hossein Nevisi, Daniel Reidenbach
2011 Electronic Proceedings in Theoretical Computer Science  
In the present paper we study the question of whether, for any given word, there exists an unambiguous 1-uniform morphism, i.e., a morphism that maps every letter in the word to an image of length 1.  ...  A morphism h is unambiguous with respect to a word w if there is no other morphism g that maps w to the same image as h.  ...  Acknowledgements The authors wish to thank the anonymous referees for their helpful remarks and suggestions.  ... 
doi:10.4204/eptcs.63.22 fatcat:7crox6fj65hstkmh777k4kfm7u

On the equivalence problem for E-pattern languages

Enno Ohlebusch, Esko Ukkonen
1997 Theoretical Computer Science  
a (linear) morphism.  ...  Now define the morphism v by v(z, ) = cawy,ac a CCZU;~~, v(z2 ) = c and v(zs ) = caw,., ac ca w,"> ac ca WY4 a.  ...  The set of variables of V appearing in cx will be denoted by W(Y A pattern a is unambiguous if, for every word w E LE,r(or), there is a unique terminal-preserving morphism IS such that ~(a) = w.  ... 
doi:10.1016/s0304-3975(96)00289-7 fatcat:whsr7q6o6rcmbl2ssk7rxia5jq

Unambiguous 1-uniform morphisms

Hossein Nevisi, Daniel Reidenbach
2013 Theoretical Computer Science  
In the present paper we study the question of whether, for any given word, there exists an unambiguous 1-uniform morphism, i. e., a morphism that maps every letter in the word to an image of length 1.  ...  A morphism σ is unambiguous with respect to a word α if there is no other morphism τ that maps α to the same image as σ.  ...  Acknowledgements The authors wish to thank the anonymous referees of both the conference [11] and the full version of this paper for their helpful remarks and suggestions.  ... 
doi:10.1016/j.tcs.2012.11.023 fatcat:bh4ph2w2bzhvrojisld4e7cgbq

Iteration of expansions — unambiguous semigroups

Jean-Camille Birget
1984 Journal of Pure and Applied Algebra  
Thus one obtains an expansion which is invariant under application of the old two expansions and thus has the properties of both (e.g., one obtains -+ with _"+ = -+ = :+", and so -+ has unambiguous 2-and  ...  ., the I.hodes expansions s', resp. s ', have unambiguous Yiesp. .$-order.  ...  Acknowledgement This work is part of my Ph.D. thesis. I learned semigroup theory from Professor John Rhodes, and I owe a lot to his inspiring ideas.  ... 
doi:10.1016/0022-4049(84)90055-0 fatcat:7yyx35drcrhtbcsqf7crxjrtma

Contents

2009 Discrete Applied Mathematics  
Zhou Reciprocal complementary Wiener numbers of trees, unicyclic graphs and bicyclic graphs 3046 D.D. Freydenberger and D. Reidenbach The unambiguity of segmented morphisms 3055 V.  ...  Stephan Facets of the (s, t)-p-path polytope 3119 H. Yaman Polyhedral analysis for the two-item uncapacitated lot-sizing problem with one-way substitution 3133 D. Ye and H.  ... 
doi:10.1016/s0166-218x(09)00289-3 fatcat:2vs3ilawtbdafalknoayunmaem

Discontinuities in pattern inference

Daniel Reidenbach
2008 Theoretical Computer Science  
of combinatorial insights into morphisms in word monoids.  ...  It is shown that the inferrability of classes of E-pattern languages is closely connected to some problems on the ambiguity of morphisms so that the technical contributions of the paper largely consist  ...  complete inner segment, the rightmost letter of left segment and the leftmost letter of the right segment of σ tf-tt,i (x j ).  ... 
doi:10.1016/j.tcs.2008.02.029 fatcat:3ihqeadzwfdnxhjff3x6usqwte

Registration Quality Filtering Improves Robustness of Voxel-Wise Analyses to the Choice of Brain Template

Nelson Gil, Michael Lipton, Roman Fleysher
2020 NeuroImage  
The approach is based on computing a "distance" between automatically-generated atlases of the subjects of interest and templates that is indicative of the extent of subject-to-template registration errors  ...  Such comparisons are made possible by registration of the images of subjects of interest onto a common brain template, such as the Johns Hopkins University (JHU) template.  ...  Acknowledgments This work was supported by the National Institute of Aging grant P01AG003949 and National Institute of Neurologic Disorders and Stroke grant R01NS082432.  ... 
doi:10.1016/j.neuroimage.2020.117657 pmid:33338620 pmcid:PMC7880909 fatcat:b5jut35zyne5pp2xrhz5nypdxi
« Previous Showing results 1 — 15 out of 881 results