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  Subjects -> MATHEMATICS (Total: 1051 journals)
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MATHEMATICS (775 journals)            First | 1 2 3 4     

Showing 401 - 538 of 538 Journals sorted alphabetically
Journal of Geological Research     Open Access   (Followers: 1)
Journal of Geovisualization and Spatial Analysis     Hybrid Journal  
Journal of Global Optimization     Hybrid Journal   (Followers: 6)
Journal of Global Research in Mathematical Archives     Open Access   (Followers: 1)
Journal of Group Theory     Hybrid Journal   (Followers: 2)
Journal of Homotopy and Related Structures     Hybrid Journal  
Journal of Honai Math     Open Access  
Journal of Humanistic Mathematics     Open Access   (Followers: 1)
Journal of Hyperbolic Differential Equations     Hybrid Journal  
Journal of Indian Council of Philosophical Research     Hybrid Journal  
Journal of Industrial Mathematics     Open Access   (Followers: 2)
Journal of Inequalities and Applications     Open Access  
Journal of Infrared, Millimeter and Terahertz Waves     Hybrid Journal   (Followers: 2)
Journal of Integrable Systems     Open Access   (Followers: 1)
Journal of K-Theory     Full-text available via subscription  
Journal of Knot Theory and Its Ramifications     Hybrid Journal   (Followers: 1)
Journal of Kufa for Mathematics and Computer     Open Access   (Followers: 1)
Journal of Liquid Chromatography & Related Technologies     Hybrid Journal   (Followers: 7)
Journal of Logical and Algebraic Methods in Programming     Hybrid Journal  
Journal of Manufacturing Systems     Full-text available via subscription   (Followers: 4)
Journal of Mathematical Analysis and Applications     Full-text available via subscription   (Followers: 4)
Journal of mathematical and computational science     Open Access   (Followers: 7)
Journal of Mathematical and Fundamental Sciences     Open Access  
Journal of Mathematical Behavior     Hybrid Journal   (Followers: 2)
Journal of Mathematical Chemistry     Hybrid Journal   (Followers: 3)
Journal of Mathematical Cryptology     Hybrid Journal   (Followers: 1)
Journal of Mathematical Extension     Open Access   (Followers: 3)
Journal of Mathematical Finance     Open Access   (Followers: 7)
Journal of Mathematical Imaging and Vision     Hybrid Journal   (Followers: 6)
Journal of Mathematical Logic     Hybrid Journal   (Followers: 2)
Journal of Mathematical Modelling and Algorithms     Hybrid Journal   (Followers: 1)
Journal of Mathematical Neuroscience     Open Access   (Followers: 9)
Journal of Mathematical Sciences     Hybrid Journal  
Journal of Mathematical Sciences and Applications     Open Access   (Followers: 2)
Journal of Mathematical Sociology     Hybrid Journal   (Followers: 3)
Journal of Mathematics     Open Access  
Journal of Mathematics and Statistics     Open Access   (Followers: 8)
Journal of Mathematics and the Arts     Hybrid Journal   (Followers: 2)
Journal of Mathematics in Industry     Open Access   (Followers: 1)
Journal of Mathematics Research     Open Access   (Followers: 6)
Journal of Metallurgy     Open Access   (Followers: 7)
Journal of Modern Mathematics Frontier     Open Access  
Journal of Multidisciplinary Modeling and Optimization     Open Access  
Journal of Multivariate Analysis     Hybrid Journal   (Followers: 13)
Journal of Natural Sciences and Mathematics Research     Open Access  
Journal of Nonlinear Analysis and Optimization : Theory & Applications     Open Access   (Followers: 4)
Journal of Nonlinear Mathematical Physics     Hybrid Journal   (Followers: 1)
Journal of Nonlinear Science     Hybrid Journal   (Followers: 1)
Journal of Numerical Cognition     Open Access  
Journal of Numerical Mathematics     Hybrid Journal   (Followers: 2)
Journal of Optimization     Open Access   (Followers: 4)
Journal of Peridynamics and Nonlocal Modeling     Hybrid Journal  
Journal of Problem Solving     Open Access   (Followers: 2)
Journal of Progressive Research in Mathematics     Open Access   (Followers: 1)
Journal of Pseudo-Differential Operators and Applications     Hybrid Journal  
Journal of Pure and Applied Algebra     Full-text available via subscription   (Followers: 4)
Journal of Quantitative Analysis in Sports     Hybrid Journal   (Followers: 8)
Journal of Quantitative Linguistics     Hybrid Journal   (Followers: 6)
Journal of Scientific Computing     Hybrid Journal   (Followers: 18)
Journal of Scientific Research     Open Access  
Journal of Symbolic Computation     Hybrid Journal   (Followers: 1)
Journal of the Australian Mathematical Society     Full-text available via subscription  
Journal of the Egyptian Mathematical Society     Open Access  
Journal of the European Mathematical Society     Full-text available via subscription   (Followers: 1)
Journal of the Indian Mathematical Society     Hybrid Journal   (Followers: 1)
Journal of the Institute of Mathematics of Jussieu     Hybrid Journal  
Journal of the London Mathematical Society     Hybrid Journal   (Followers: 2)
Journal of the Nigerian Mathematical Society     Open Access   (Followers: 1)
Journal of Theoretical and Applied Physics     Open Access   (Followers: 8)
Journal of Topology and Analysis     Hybrid Journal  
Journal of Transport and Supply Chain Management     Open Access   (Followers: 14)
Journal of Turbulence     Hybrid Journal   (Followers: 7)
Journal of Uncertainty Analysis and Applications     Open Access  
Journal of Universal Mathematics     Open Access  
Journal of Urban Regeneration & Renewal     Full-text available via subscription   (Followers: 10)
Journal of Water and Land Development     Open Access   (Followers: 3)
JRAMathEdu : Journal of Research and Advances in Mathematics Education     Open Access   (Followers: 3)
JURING (Journal for Research in Mathematics Learning)     Open Access   (Followers: 1)
Jurnal Ilmiah AdMathEdu     Open Access  
Jurnal Matematika     Open Access   (Followers: 1)
Jurnal Matematika Integratif     Open Access  
Jurnal Matematika, Sains, Dan Teknologi     Open Access  
Jurnal Natural     Open Access  
Jurnal Pendidikan Matematika Raflesia     Open Access  
Jurnal Penelitian Pembelajaran Matematika Sekolah     Open Access  
Jurnal Penelitian Sains (JPS)     Open Access  
Jurnal Riset Pendidikan Matematika     Open Access  
Jurnal Sains Matematika dan Statistika     Open Access  
Jurnal Tadris Matematika     Open Access  
Jurnal Teknologi dan Sistem Komputer     Open Access  
Kreano, Jurnal Matematika Kreatif-Inovatif     Open Access   (Followers: 5)
Le Matematiche     Open Access  
Learning and Teaching Mathematics     Full-text available via subscription   (Followers: 7)
Lettera Matematica     Hybrid Journal  
Limits : Journal of Mathematics and Its Applications     Open Access   (Followers: 1)
Linear Algebra and its Applications     Full-text available via subscription   (Followers: 22)
Linear and Multilinear Algebra     Hybrid Journal   (Followers: 8)
Lithuanian Mathematical Journal     Hybrid Journal  
LMS Journal of Computation and Mathematics     Free  
Lobachevskii Journal of Mathematics     Open Access  
Logic and Analysis     Hybrid Journal  
Logic Journal of the IGPL     Hybrid Journal  
Logica Universalis     Hybrid Journal  
manuscripta mathematica     Hybrid Journal  
MaPan : Jurnal Matematika dan Pembelajaran     Open Access  
Marine Genomics     Hybrid Journal   (Followers: 2)
Matemáticas, Educación y Sociedad     Open Access  
Matematicheskie Zametki     Full-text available via subscription  
Matematika     Open Access  
Matematychni Studii     Open Access  
Mathematica Eterna     Open Access  
Mathematica Scandinavica     Open Access   (Followers: 1)
Mathematica Slovaca     Hybrid Journal   (Followers: 1)
Mathematical and Computational Forestry & Natural-Resource Sciences     Free  
Mathematical Communications     Open Access  
Mathematical Computation     Open Access   (Followers: 1)
Mathematical Geosciences     Hybrid Journal   (Followers: 3)
Mathematical Medicine and Biology: A Journal of the IMA     Hybrid Journal   (Followers: 1)
Mathematical Methods in the Applied Sciences     Hybrid Journal   (Followers: 4)
Mathematical Methods of Statistics     Hybrid Journal   (Followers: 4)
Mathematical Modelling and Analysis     Open Access   (Followers: 1)
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 5)
Mathematical Modelling of Natural Phenomena     Full-text available via subscription   (Followers: 1)
Mathematical Models and Methods in Applied Sciences     Hybrid Journal   (Followers: 2)
Mathematical Notes     Hybrid Journal  
Mathematical Proceedings of the Cambridge Philosophical Society     Full-text available via subscription   (Followers: 1)
Mathematical Programming Computation     Hybrid Journal   (Followers: 3)
Mathematical Sciences     Open Access  
Mathematical Social Sciences     Hybrid Journal   (Followers: 1)
Mathematical Theory and Modeling     Open Access   (Followers: 13)
Mathematical Thinking and Learning     Hybrid Journal   (Followers: 3)
Mathematics and Statistics     Open Access   (Followers: 5)
Mathematics Education Journal     Open Access   (Followers: 1)
Mathematics Education Research Journal     Partially Free   (Followers: 17)
Mathematics in Science and Engineering     Full-text available via subscription  
Mathematics of Control, Signals, and Systems (MCSS)     Hybrid Journal   (Followers: 5)
Mathematics of Quantum and Nano Technologies     Open Access  
Mathématiques et sciences humaines     Open Access   (Followers: 7)
Mathematische Annalen     Hybrid Journal   (Followers: 1)
Mathematische Nachrichten     Hybrid Journal   (Followers: 1)
Mathematische Semesterberichte     Hybrid Journal  
Mathematische Zeitschrift     Hybrid Journal   (Followers: 1)
MATI : Mathematical Aspects of Topological Indeces     Open Access  
MATICS     Open Access   (Followers: 2)
Matrix Science Mathematic     Open Access   (Followers: 1)
Measurement Science Review     Open Access   (Followers: 3)
Mediterranean Journal of Mathematics     Hybrid Journal  
Memetic Computing     Hybrid Journal  
Mendel : Soft Computing Journal     Open Access  
Metaheuristics     Hybrid Journal  
Metals and Materials International     Hybrid Journal  
Metascience     Hybrid Journal   (Followers: 1)
Milan Journal of Mathematics     Hybrid Journal  
Mitteilungen der DMV     Hybrid Journal  
MLQ- Mathematical Logic Quarterly     Hybrid Journal  
Monatshefte fur Mathematik     Hybrid Journal  
Moroccan Journal of Pure and Applied Analysis     Open Access   (Followers: 4)
Moscow University Mathematics Bulletin     Hybrid Journal  
MSOR Connections     Open Access   (Followers: 1)
Multiscale Modeling and Simulation     Hybrid Journal   (Followers: 3)
MUST : Journal of Mathematics Education, Science and Technology     Open Access   (Followers: 1)
Nagoya Mathematical Journal     Hybrid Journal  
Nano Research     Hybrid Journal   (Followers: 3)
Nanotechnologies in Russia     Hybrid Journal   (Followers: 1)
Natural Resource Modeling     Hybrid Journal  
New Mathematics and Natural Computation     Hybrid Journal  
Nonlinear Analysis : Modelling and Control     Open Access   (Followers: 1)
Nonlinear Analysis : Theory, Methods & Applications     Hybrid Journal   (Followers: 1)
Nonlinear Analysis: Hybrid Systems     Hybrid Journal  
Nonlinear Analysis: Real World Applications     Hybrid Journal   (Followers: 2)
Nonlinear Differential Equations and Applications NoDEA     Hybrid Journal  
Nonlinear Engineering     Open Access  
Nonlinear Oscillations     Hybrid Journal   (Followers: 1)
North Carolina Journal of Mathematics and Statistics     Open Access  
North-Holland Mathematical Library     Full-text available via subscription   (Followers: 1)
North-Holland Mathematics Studies     Full-text available via subscription  
North-Holland Series in Applied Mathematics and Mechanics     Full-text available via subscription   (Followers: 1)
Note di Matematica     Open Access  
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Numeracy : Advancing Education in Quantitative Literacy     Open Access  
Numerical Analysis and Applications     Hybrid Journal   (Followers: 1)
Numerical Functional Analysis and Optimization     Hybrid Journal   (Followers: 2)
Numerical Linear Algebra with Applications     Hybrid Journal   (Followers: 6)
Numerical Mathematics : Theory, Methods and Applications     Full-text available via subscription  
Numerische Mathematik     Hybrid Journal  
Open Journal of Discrete Mathematics     Open Access   (Followers: 5)
Open Journal of Modelling and Simulation     Open Access   (Followers: 1)
Open Mathematics     Open Access   (Followers: 1)
Operations Research Letters     Hybrid Journal   (Followers: 11)
Optimization Letters     Hybrid Journal   (Followers: 2)
Optimization Methods and Software     Hybrid Journal   (Followers: 8)
Opuscula Mathematica     Open Access   (Followers: 108)
Order     Hybrid Journal  
ORiON     Open Access  
P-Adic Numbers, Ultrametric Analysis, and Applications     Hybrid Journal  
PAMM : Proceedings in Applied Mathematics and Mechanics     Free   (Followers: 1)
Parallel Processing Letters     Hybrid Journal   (Followers: 3)
Peking Mathematical Journal     Hybrid Journal  
Periodica Mathematica Hungarica     Full-text available via subscription   (Followers: 1)
Perspectivas da Educação Matemática     Open Access  

  First | 1 2 3 4     

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Periodica Mathematica Hungarica
Journal Prestige (SJR): 0.466
Citation Impact (citeScore): 1
Number of Followers: 1  
  Full-text available via subscription Subscription journal
ISSN (Print) 1588-2829 - ISSN (Online) 0031-5303
Published by Springer-Verlag Homepage  [2573 journals]
  • Bounding univariate and multivariate reducible polynomials with restricted
    • Abstract: Abstract Let \(d,H \geqslant 2\) , \(m, u \geqslant 0\) be some integers satisfying \(m+u \leqslant d\) . Consider a set of univariate integer polynomials of degree d whose m coefficients for the highest powers of x and u coefficients for the lowest powers of x are fixed, whereas the remaining \(g=d-m-u+1\) coefficients are all bounded by H in absolute value. We show that among those \((2H+1)^g\) polynomials at most \(c d(2H+1)^{g-1}(\log (2H))^{\delta }\) are reducible over \(\mathbb Q\) , where the constant \(c>0\) depends only on two extreme coefficients (if they are fixed) and does not depend on d and H. Here, \(\delta =2\) if \(m=u=0\) ; \(\delta =1\) if only one of m, u is zero; \(\delta =0\) if none of m, u is zero. This estimate is better than the previous one in certain range of d and H. We also prove an estimate for the number of integer reducible polynomials in \(n \geqslant 2\) variables of degree \(d \geqslant 1\) in each variable and height at most \(H \geqslant 1\) . It is completely explicit in terms of n, d, H and implies that the probability for such a polynomial to be reducible tends to zero as \(\max (n,d,H) \rightarrow \infty \) . The condition \(n \geqslant 2\) is essential in the proof: despite some recent progress the problem in general remains open for \(n=1\) .
      PubDate: 2019-03-01
  • Some applications of S -restricted set partitions
    • Abstract: Abstract In the paper, the authors present several new relations and applications for the combinatorial sequence that counts the possible partitions of a finite set with the restriction that the size of each block is contained in a given set. One of the main applications is in the study of lonesum matrices.
      PubDate: 2019-03-01
  • On the distribution of partial sums of irrational rotations
    • Abstract: Abstract For an irrational \(\alpha \) , we investigate the sums \(\sum _{i=1}^n \left( \{i \alpha \} - \frac{1}{2} \right) \) and \(\sum _{i=1}^n \left\{ \left( \{i \alpha \} - \frac{1}{2} \right) ^2 - \frac{1}{12} \right\} \) . We discuss exact formulae and asymptotic estimates for these sums and point out interesting geometrical properties of their graphs in the case when the continued fraction expansion of \(\alpha \) has a large isolated partial quotient.
      PubDate: 2019-03-01
  • On two theorems of positional games
    • Abstract: Abstract I give fully detailed proofs of two important theorems—the exact solution of the weak clique game and the compactness theorem—in the theory of positional games. Both results were published several years ago, including an outline of the proofs that explained the basic idea, but left some technical details to the reader. Unfortunately, in both cases these details turned out to be highly non-trivial. Several mathematicians asked me for help; asked me to clarify the missing details. This is why I felt obliged to write this paper.
      PubDate: 2019-03-01
  • On the freeness of Böröczky line arrangements
    • Abstract: Abstract In the present note, we focus on the freeness and some combinatorial properties of line arrangements in the projective plane having only double and triple points. The main result shows that for this class of line arrangements the freeness property is combinatorially determined. As a corollary, we show that Böröczky line arrangements in the sense of Füredi and Palásti (Proc Am Math Soc 92(4):561–566, 1984), except exactly three cases, are not free.
      PubDate: 2019-03-01
  • Ricci solitons and geometry of four dimensional Einstein-like neutral Lie
    • Abstract: Abstract We classify left-invariant Einstein-like metrics of neutral signature, over four-dimensional Lie groups. Several geometric properties such as being conformally flat, existing Ricci solitons and Walker structures are exhibited.
      PubDate: 2019-03-01
  • On the lattice of principal generalized topologies
    • Abstract: Abstract In this paper we investigate the structure of the complete lattice of principal generalized topologies, employing the notion of ultratopology. On any partially ordered set we introduce a generalized topology. The existence of an anti-isomorphism between principal generalized topologies and preorder relations on a set is proposed. After determining the very basic topological properties therein, we will show that each generalized topology has a lattice complement in principal generalized topologies.
      PubDate: 2019-03-01
  • On the rank of the 2-class group of an extension of degree 8 over
           $$\mathbb {Q}$$ Q
    • Abstract: Abstract Let K be an imaginary cyclic quartic number field whose 2-class group is nontrivial, it is known that there exists at least one unramified quadratic extension F of K. In this paper, we compute the rank of the 2-class group of the field F.
      PubDate: 2019-03-01
  • Tauberian conditions on some slowly decreasing sequences
    • Abstract: Abstract We present some Tauberian conditions to recover Cesàro summability of a sequence out of the product methods of Abel and Cesàro summability of the sequence. Moreover, we generalize some classical Tauberian theorems, such as the Hardy–Littlewood theorem, the generalized Littlewood theorem for Abel summability method.
      PubDate: 2019-03-01
  • Partial actions and an embedding theorem for inverse semigroups
    • Abstract: Abstract We give a simple construction involving partial actions which permits us to obtain an easy proof of a weakened version of L. O’Carroll’s theorem on idempotent pure extensions of inverse semigroups.
      PubDate: 2019-03-01
  • Einstein–Weyl structures on almost cosymplectic manifolds
    • Abstract: Abstract In this article, we study Einstein–Weyl structures on almost cosymplectic manifolds. First we prove that an almost cosymplectic \((\kappa ,\mu )\) -manifold is Einstein or cosymplectic if it admits a closed Einstein–Weyl structure or two Einstein–Weyl structures. Next for a three dimensional compact almost \(\alpha \) -cosymplectic manifold admitting closed Einstein–Weyl structures, we prove that it is Ricc-flat. Further, we show that an almost \(\alpha \) -cosymplectic admitting two Einstein–Weyl structures is either Einstein or \(\alpha \) -cosymplectic, provided that its Ricci tensor is commuting. Finally, we prove that a compact K-cosymplectic manifold with a closed Einstein–Weyl structure or two special Einstein–Weyl structures is cosymplectic.
      PubDate: 2019-01-17
  • Legendrian non-simple two-bridge knots
    • Abstract: Abstract By examining knot Floer homology, we extend a result of Ozsváth and Stipsicz and show further infinitely many Legendrian and transversely non-simple knot types among two-bridge knots. We give sufficient conditions of Legendrian and transverse non-simplicity on the continued fraction expansion of the corresponding rational number.
      PubDate: 2019-01-02
  • Bivariate Hermite interpolation on the exponential curve
    • Abstract: Abstract We study Hermite interpolation problems on the exponential curve \(y=e^x\) in \(\mathbb {R}^2\) . We construct some kind of regular Hermite interpolation schemes and investigate continuity properties of interpolation polynomials with respect to interpolation conditions.
      PubDate: 2018-12-19
  • On volumes of truncated tetrahedra with constrained edge lengths
    • Abstract: Abstract Truncated tetrahedra are the fundamental building blocks of hyperbolic 3-manifolds with geodesic boundary. The study of their geometric properties (in particular, of their volume) has applications also in other areas of low-dimensional topology, like the computation of quantum invariants of 3-manifolds and the use of variational methods in the study of circle packings on surfaces. The Lobachevsky–Schläfli formula neatly describes the behaviour of the volume of truncated tetrahedra with respect to dihedral angles, while the dependence of volume on edge lengths is worse understood. In this paper we prove that, for every \(\ell <\ell _0\) , where \(\ell _0\) is an explicit constant, the regular truncated tetrahedron of edge length \(\ell \) maximizes the volume among truncated tetrahedra whose edge lengths are all not smaller than \(\ell \) . This result provides a fundamental step in the computation of the ideal simplicial volume of an infinite family of hyperbolic 3-manifolds with geodesic boundary.
      PubDate: 2018-12-17
  • On the structure of additive systems of integers
    • Abstract: Abstract A sum-and-distance system is a collection of finite sets of integers such that the sums and differences formed by taking one element from each set generate a prescribed arithmetic progression. Such systems, with two component sets, arise naturally in the study of matrices with symmetry properties and consecutive integer entries. Sum systems are an analogous concept where only sums of elements are considered. We establish a bijection between sum systems and sum-and-distance systems of corresponding size, and show that sum systems are equivalent to principal reversible cuboids, which are tensors with integer entries and a symmetry of ‘reversible square’ type. We prove a structure theorem for principal reversible cuboids, which gives rise to an explicit construction formula for all sum systems in terms of joint ordered factorisations of their component set cardinalities.
      PubDate: 2018-12-17
  • On the taxicab distance sum function and its applications in discrete
    • Abstract: Abstract Let a finite set \(F\subset \mathbb {R}^n\) be given. The taxicab distance sum function is defined as the sum of the taxicab distances from the elements (focuses) of the so-called focal set F. The sublevel sets of the taxicab distance sum function are called generalized conics because the boundary points have the same average taxicab distance from the focuses. In case of a classical conic (ellipse) the focal set contains exactly two different points and the distance taken to be averaged is the Euclidean one. The sublevel sets of the taxicab distance sum function can be considered as its generalizations. We prove some geometric (convexity), algebraic (semidefinite representation) and extremal (the problem of the minimizer) properties of the generalized conics and the taxicab distance sum function. We characterize its minimizer and we give an upper and lower bound for the extremal value. A continuity property of the mapping sending a finite subset F to the taxicab distance sum function is also formulated. Finally we present some applications in discrete tomography. If the rectangular grid determined by the coordinates of the elements in \(F\subset \mathbb {R}^2\) is given then the number of points in F along the directions parallel to the sides of the grid is a kind of tomographic information. We prove that it is uniquely determined by the function measuring the average taxicab distance from the focal set F and vice versa. Using the method of the least average values we present an algorithm to reconstruct F with a given number of points along the directions parallel to the sides of the grid.
      PubDate: 2018-12-17
  • On the algebraic and arithmetic structure of the monoid of product-one
           sequences II
    • Abstract: Abstract Let G be a finite group and \(G'\) its commutator subgroup. By a sequence over G, we mean a finite unordered sequence of terms from G, where repetition is allowed, and we say that it is a product-one sequence if its terms can be ordered such that their product equals the identity element of G. The monoid \({\mathcal {B}} (G)\) of all product-one sequences over G is a finitely generated C-monoid whence it has a finite commutative class semigroup. It is well-known that the class semigroup is a group if and only if G is abelian (equivalently, \({\mathcal {B}} (G)\) is Krull). In the present paper we show that the class semigroup is Clifford (i.e., a union of groups) if and only if \( G' \le 2\) if and only if \({\mathcal {B}} (G)\) is seminormal, and we study sets of lengths in \({\mathcal {B}} (G)\) .
      PubDate: 2018-12-17
  • Covering and Euler cycles on non-oriented graphs
    • Abstract: Abstract A covering cycle is a closed path that traverses each edge of a graph at least once. Two cycles are equivalent if one is a cyclic permutation of the other. We compute the number of equivalence classes of non-periodic covering cycles of given length in a non-oriented connected graph. A special case is the number of Euler cycles (covering cycles that cover each edge of the graph exactly once) in the non-oriented graph. We obtain an identity relating the numbers of covering cycles of any length in a graph to a product of determinants.
      PubDate: 2018-12-01
  • On the Sylvester–Gallai and the orchard problem for pseudoline
    • Abstract: Abstract We study a non-trivial extreme case of the orchard problem for 12 pseudolines and we provide a complete classification of pseudoline arrangements having 19 triple points and 9 double points. We have also classified those that can be realized with straight lines. They include new examples different from the known example of Böröczky. Since Melchior’s inequality also holds for arrangements of pseudolines, we are able to deduce that some combinatorial point-line configurations cannot be realized using pseudolines. In particular, this gives a negative answer to one of Grünbaum’s problems. We formulate some open problems which involve our new examples of line arrangements.
      PubDate: 2018-12-01
  • Repdigits as sums of three Pell numbers
    • Abstract: Abstract In this paper, all base 10 repdigits expressible as sums of three Pell numbers are found.
      PubDate: 2018-12-01
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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Fax: +00 44 (0)131 4513327
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