Search results for "MATHEMATICS"
showing 10 items of 22031 documents
On Prefix Normal Words
2011
We present a new class of binary words: the prefix normal words. They are defined by the property that for any given length $k$, no factor of length $k$ has more $a$'s than the prefix of the same length. These words arise in the context of indexing for jumbled pattern matching (a.k.a. permutation matching or Parikh vector matching), where the aim is to decide whether a string has a factor with a given multiplicity of characters, i.e., with a given Parikh vector. Using prefix normal words, we give the first non-trivial characterization of binary words having the same set of Parikh vectors of factors. We prove that the language of prefix normal words is not context-free and is strictly contaiâŠ
Permutations of zero-sumsets in a finite vector space
2020
Abstract In this paper, we consider a finite-dimensional vector space đ« {{\mathcal{P}}} over the Galois field GF ⥠( p ) {\operatorname{GF}(p)} , with p being an odd prime, and the family ⏠k x {{\mathcal{B}}_{k}^{x}} of all k-sets of elements of đ« {\mathcal{P}} summing up to a given element x. The main result of the paper is the characterization, for x = 0 {x=0} , of the permutations of đ« {\mathcal{P}} inducing permutations of ⏠k 0 {{\mathcal{B}}_{k}^{0}} as the invertible linear mappings of the vector space đ« {\mathcal{P}} if p does not divide k, and as the invertible affinities of the affine space đ« {\mathcal{P}} if p divides k. The same question is answered also in the case where âŠ
The effect of noise, a constant background, and bit depth on the phase retrieval of pure phase objects
2021
Acknowledgements â The authors are supported by the postdoctoral project (1.1.1.2/16/I/001; 1.1.1.2/ VIAA/1/16/199, State Education Development Agency, Republic of Latvia).
Codimensions of algebras with additional structures
2022
Let A be an associative algebra endowed with an automorphism or an antiautomorphism phi of order <= 2. One associates to A, in a natural way, a numerical sequence c(n)(phi)(A), n = 1, 2, ... , called the sequence of phi-codimensions of A which is the main tool for the quantitative investigation of the polynomial identities satisfied by A. In [13] it was proved that such a sequence is eventually nondecreasing in case phi is an antiautomorphism. Here we prove that it still holds in case phi is an automorphism and present some recent results about the asymptotics of c(n)(phi)(A).
A phenomenological view of pictures in teaching and a novel method for analysing them
2014
In this paper a novel method for analysing the content and teaching potential of pictures is presented. It is the four-field method, which is based on phenomenological thoughts about human experience, which combines factual knowledge with emotions and personal and social meanings. Â A biological example is given. Around this idea a course unit for using pictures in science teaching was organized. It was used in the training of both primary and secondary level teachers. From picture analysis the course unit proceeds to planning the use of pictures in teaching. A classification of the teaching functions of pictures is presented.
Specific distribution of cross-sectional area in each hamstring muscle of sprint runners and relationship between those and sprint performance
2018
Modéliser un demi-cercle et autres questions de poids nuls
2018
National audience; Les courbes de Bézier rationnelles avec des points pondérés peinent à prendre en compte certaines situations élémentaires comme la modélisation d'un demi-cercle avec une courbe de degré 2. Dans cet article nous mon-trons comment l'utilisation de courbes de Bézier rationnelles avec des points massiques résout ce problÚme. Plus largement, nous montrons aussi que la formulation usuelle de Bézier rationnelles n'est pas complÚte.
Introduction à la modélisation de l'écriture manuscrite par des courbes Bézier Rationnelles massiques
2019
National audience; Lâarticle est une introduction Ă la modĂ©lisation de lâĂ©criture manuscrite. La reprĂ©sentation de lâĂ©criture cursive in- terfĂšre, selon lâapproche hors ligne ou en ligne, sur la robustesse des algorithmes de reconnaissance des caractĂšres manuscrits, de lâidentification des auteurs et de leur signature. Les caractĂ©ristiques de base de lâĂ©criture cursive que sont les traits et leur inclinaisons, les boucles, les pleins et dĂ©liĂ©s peuvent ĂȘtre modĂ©lisĂ©s par des courbes. Des mĂ©thodes existent. Elles reposent sur les B-splines et leur points de contrĂŽle. Dans un premier temps, des traits, les auteurs proposent une modĂ©lisation, rebroussements, boucles, arrondis, pleins et dĂ©liĂ©s.âŠ
Sequestration of biogenic amines by alginic and fulvic acids.
2006
The interaction of natural (alginic and fulvic acids) and synthetic (polyacrylic acid 2.0 kDa) polyelectrolytes with some protonated polyamines [diamines: ethylendiamine, 1,4-diaminobutane (or putrescine), 1,5-diaminopentane (or cadaverine); triamines: N-(3-aminopropyl)-1,4diaminobutane (or spermidine), diethylenetriamine; tetramine: N.N'-bis(3-aminopropyl)-1,4-diaminobutane (or spermine); pentamine: tetraethylene-pentamine; hexamine: pentaethylenehexamine] was studied at T=25 degrees C by potentiometry and calorimetry. Measurements were performed without supporting electrolyte, in order to avoid interference, and results were reported at I=0 mol L(-1). For all the systems, the formation ofâŠ
Embeddings of Danielewski hypersurfaces
2008
In this thesis, we study a class of hypersurfaces in $\mathbb{C}^3$, called \emph{Danielewski hypersurfaces}. This means hypersurfaces $X_{Q,n}$ defined by an equation of the form $x^ny=Q(x,z)$ with $n\in\mathbb{N}_{\geq1}$ and $\deg_z(Q(x,z))\geq2$. We give their complete classification, up to isomorphism, and up to equivalence via an automorphism of $\mathbb{C}^3$. In order to do that, we introduce the notion of standard form and show that every Danielewski hypersurface is isomorphic (by an algorithmic procedure) to a Danielewski hypersurface in standard form. This terminology is relevant since every isomorphism between two standard forms can be extended to an automorphism of the ambiant âŠ