Subjects -> MATHEMATICS (Total: 1013 journals)
    - APPLIED MATHEMATICS (92 journals)
    - GEOMETRY AND TOPOLOGY (23 journals)
    - MATHEMATICS (714 journals)
    - MATHEMATICS (GENERAL) (45 journals)
    - NUMERICAL ANALYSIS (26 journals)
    - PROBABILITIES AND MATH STATISTICS (113 journals)

MATHEMATICS (714 journals)            First | 1 2 3 4 | Last

Showing 201 - 400 of 538 Journals sorted alphabetically
Educação Matemática Debate     Open Access  
Edumatica : Jurnal Pendidikan Matematika     Open Access  
EduMatSains     Open Access  
Electronic Journal of Differential Equations     Open Access  
Electronic Journal of Graph Theory and Applications     Open Access   (Followers: 3)
Em Teia : Revista de Educação Matemática e Tecnológica Iberoamericana     Open Access  
Emergent Scientist     Open Access  
Energy for Sustainable Development     Hybrid Journal   (Followers: 13)
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Entropy     Open Access   (Followers: 5)
ESAIM: Control Optimisation and Calculus of Variations     Open Access   (Followers: 2)
Euclid     Open Access  
European Journal of Applied Mathematics     Hybrid Journal  
European Journal of Combinatorics     Full-text available via subscription   (Followers: 3)
European Journal of Mathematics     Hybrid Journal   (Followers: 1)
European Scientific Journal     Open Access   (Followers: 1)
Examples and Counterexamples     Open Access  
Experimental Mathematics     Hybrid Journal   (Followers: 5)
Expositiones Mathematicae     Hybrid Journal   (Followers: 2)
Extracta Mathematicae     Open Access  
Facta Universitatis, Series : Mathematics and Informatics     Open Access  
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 5)
Fixed Point Theory and Applications     Open Access  
Formalized Mathematics     Open Access  
Forum of Mathematics, Pi     Open Access   (Followers: 1)
Forum of Mathematics, Sigma     Open Access   (Followers: 1)
Foundations and Trends® in Econometrics     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Networking     Full-text available via subscription   (Followers: 1)
Foundations and Trends® in Stochastic Systems     Full-text available via subscription   (Followers: 1)
Foundations and Trends® in Theoretical Computer Science     Full-text available via subscription   (Followers: 1)
Foundations of Computational Mathematics     Hybrid Journal  
Fractal and Fractional     Open Access  
Fractals     Hybrid Journal   (Followers: 1)
Frontiers of Mathematics in China     Hybrid Journal  
Fuel Cells Bulletin     Full-text available via subscription   (Followers: 9)
Functional Analysis and Other Mathematics     Hybrid Journal   (Followers: 4)
Fundamental Journal of Mathematics and Applications     Open Access  
Funktsional'nyi Analiz i ego Prilozheniya     Full-text available via subscription  
Fuzzy Optimization and Decision Making     Hybrid Journal   (Followers: 8)
Game Theory     Open Access   (Followers: 2)
Games     Open Access   (Followers: 4)
Games and Economic Behavior     Hybrid Journal   (Followers: 25)
Gamm - Mitteilungen     Hybrid Journal  
GANIT : Journal of Bangladesh Mathematical Society     Open Access  
GEM - International Journal on Geomathematics     Hybrid Journal   (Followers: 1)
General Mathematics     Open Access  
Glasgow Mathematical Journal     Full-text available via subscription  
Global Journal of Mathematical Sciences     Full-text available via subscription  
Graphs and Combinatorics     Hybrid Journal   (Followers: 4)
Grey Systems : Theory and Application     Hybrid Journal  
Groups, Complexity, Cryptology     Open Access   (Followers: 2)
GSTF Journal of Mathematics, Statistics and Operations Research     Open Access   (Followers: 1)
Historia Mathematica     Full-text available via subscription  
Historical Methods: A Journal of Quantitative and Interdisciplinary History     Hybrid Journal   (Followers: 28)
IMA Journal of Applied Mathematics     Hybrid Journal  
IMA Journal of Numerical Analysis - advance access     Hybrid Journal  
ImmunoInformatics     Open Access   (Followers: 1)
Indagationes Mathematicae     Open Access  
Indian Journal of Pure and Applied Mathematics     Hybrid Journal   (Followers: 4)
Indonesian Journal of Combinatorics     Open Access  
Indonesian Journal of Science and Mathematics Education     Open Access   (Followers: 1)
Infinite Dimensional Analysis, Quantum Probability and Related Topics     Hybrid Journal   (Followers: 1)
Infinity Jurnal Matematika dan Aplikasinya     Open Access   (Followers: 3)
Information and Inference     Free  
InfoTekJar : Jurnal Nasional Informatika dan Teknologi Jaringan     Open Access  
InfraMatics     Open Access  
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 110)
International Electronic Journal of Algebra     Open Access  
International Journal for Numerical Methods in Engineering     Hybrid Journal   (Followers: 35)
International Journal for Numerical Methods in Fluids     Hybrid Journal   (Followers: 19)
International Journal of Advanced Mathematical Sciences     Open Access  
International Journal of Advanced Mechatronic Systems     Hybrid Journal   (Followers: 2)
International Journal of Advanced Research in Mathematics     Open Access  
International Journal of Advances in Engineering Sciences and Applied Mathematics     Hybrid Journal   (Followers: 10)
International Journal of Algebra and Computation     Hybrid Journal   (Followers: 1)
International Journal of Algebra and Statistics     Open Access   (Followers: 3)
International Journal of Applied and Computational Mathematics     Hybrid Journal  
International Journal of Applied Mathematical Research     Open Access   (Followers: 1)
International Journal of Applied Mathematics and Computer Science     Open Access   (Followers: 7)
International Journal of Applied Mechanics     Hybrid Journal   (Followers: 8)
International Journal of Applied Nonlinear Science     Hybrid Journal  
International Journal of Autonomic Computing     Hybrid Journal   (Followers: 1)
International Journal of Bifurcation and Chaos     Hybrid Journal   (Followers: 4)
International Journal of Biomathematics     Hybrid Journal   (Followers: 2)
International Journal of Computational Complexity and Intelligent Algorithms     Hybrid Journal  
International Journal of Computational Economics and Econometrics     Hybrid Journal   (Followers: 6)
International Journal of Computational Geometry and Applications     Hybrid Journal   (Followers: 2)
International Journal of Computational Intelligence and Applications     Hybrid Journal   (Followers: 2)
International Journal of Computational Methods     Hybrid Journal   (Followers: 4)
International Journal of Computer Processing Of Languages     Hybrid Journal   (Followers: 1)
International Journal of Control, Automation and Systems     Hybrid Journal   (Followers: 15)
International Journal of Dynamical Systems and Differential Equations     Hybrid Journal   (Followers: 1)
International Journal of Economics and Accounting     Hybrid Journal   (Followers: 1)
International Journal of Foundations of Computer Science     Hybrid Journal   (Followers: 3)
International Journal of Fuzzy Computation and Modelling     Hybrid Journal   (Followers: 2)
International Journal of Image and Graphics     Hybrid Journal   (Followers: 5)
International Journal of Industrial Electronics and Drives     Hybrid Journal   (Followers: 3)
International Journal of Low-Carbon Technologies     Open Access   (Followers: 1)
International Journal of Mathematical Education in Science and Technology     Hybrid Journal   (Followers: 9)
International Journal of Mathematical Modelling & Computations     Open Access   (Followers: 3)
International Journal of Mathematical Modelling and Numerical Optimisation     Hybrid Journal   (Followers: 5)
International Journal of Mathematical Sciences and Computing     Open Access  
International Journal of Mathematics     Hybrid Journal   (Followers: 4)
International Journal of Mathematics & Computation     Full-text available via subscription  
International Journal of Mathematics and Mathematical Sciences     Open Access   (Followers: 4)
International Journal of Mathematics in Operational Research     Hybrid Journal   (Followers: 2)
International Journal of Metaheuristics     Hybrid Journal   (Followers: 1)
International Journal of Modelling in Operations Management     Hybrid Journal   (Followers: 2)
International Journal of Modern Nonlinear Theory and Application     Open Access   (Followers: 1)
International Journal of Number Theory     Hybrid Journal   (Followers: 1)
International Journal of Partial Differential Equations     Open Access   (Followers: 2)
International Journal of Polymer Science     Open Access   (Followers: 25)
International Journal of Pure Mathematical Sciences     Open Access  
International Journal of Reliability, Quality and Safety Engineering     Hybrid Journal   (Followers: 14)
International Journal of Research in Undergraduate Mathematics Education     Hybrid Journal   (Followers: 4)
International Journal of Sediment Research     Full-text available via subscription   (Followers: 2)
International Journal of Shape Modeling     Hybrid Journal   (Followers: 1)
International Journal of Theoretical and Mathematical Physics     Open Access   (Followers: 13)
International Journal of Trends in Mathematics Education Research     Open Access   (Followers: 4)
International Journal of Ultra Wideband Communications and Systems     Hybrid Journal  
International Journal of Wavelets, Multiresolution and Information Processing     Hybrid Journal  
International Journal on Artificial Intelligence Tools     Hybrid Journal   (Followers: 9)
International Mathematics Research Notices     Hybrid Journal   (Followers: 1)
Internet Mathematics     Hybrid Journal   (Followers: 1)
Inventiones mathematicae     Hybrid Journal   (Followers: 2)
Inverse Problems in Science and Engineering     Hybrid Journal   (Followers: 3)
Investigations in Mathematics Learning     Hybrid Journal  
Iranian Journal of Optimization     Open Access   (Followers: 2)
Israel Journal of Mathematics     Hybrid Journal  
Ithaca : Viaggio nella Scienza     Open Access  
ITM Web of Conferences     Open Access  
Izvestiya Rossiiskoi Akademii Nauk. Seriya Matematicheskaya     Full-text available via subscription  
Jahresbericht der Deutschen Mathematiker-Vereinigung     Hybrid Journal  
Japan Journal of Industrial and Applied Mathematics     Hybrid Journal  
Japanese Journal of Mathematics     Hybrid Journal  
JIPM (Jurnal Ilmiah Pendidikan Matematika)     Open Access  
JMPM : Jurnal Matematika dan Pendidikan Matematika     Open Access  
JOHME : Journal of Holistic Mathematics Education     Open Access   (Followers: 2)
Johnson Matthey Technology Review     Open Access  
Jornal Internacional de Estudos em Educação Matemática     Open Access  
Journal d'Analyse Mathématique     Hybrid Journal   (Followers: 2)
Journal de Mathématiques Pures et Appliquées     Full-text available via subscription   (Followers: 3)
Journal for Research in Mathematics Education     Full-text available via subscription   (Followers: 28)
Journal für Mathematik-Didaktik     Hybrid Journal  
Journal of Advanced Mathematics and Applications     Full-text available via subscription   (Followers: 1)
Journal of Algebra     Full-text available via subscription   (Followers: 3)
Journal of Algebra and Its Applications     Hybrid Journal   (Followers: 3)
Journal of Algebraic Combinatorics     Hybrid Journal   (Followers: 3)
Journal of Algorithms & Computational Technology     Open Access  
Journal of Applied Mathematics     Open Access   (Followers: 3)
Journal of Applied Mathematics and Computing     Hybrid Journal  
Journal of Applied Mathematics, Statistics and Informatics     Open Access   (Followers: 1)
Journal of Artificial Intelligence and Data Mining     Open Access   (Followers: 10)
Journal of Classification     Hybrid Journal   (Followers: 5)
Journal of Combinatorial Designs     Hybrid Journal   (Followers: 4)
Journal of Combinatorial Optimization     Hybrid Journal   (Followers: 7)
Journal of Combinatorial Theory, Series A     Full-text available via subscription   (Followers: 5)
Journal of Combinatorial Theory, Series B     Full-text available via subscription   (Followers: 3)
Journal of Complex Analysis     Open Access   (Followers: 2)
Journal of Complex Networks     Hybrid Journal   (Followers: 1)
Journal of Complexity     Hybrid Journal   (Followers: 6)
Journal of Computational and Applied Mathematics     Hybrid Journal   (Followers: 6)
Journal of Computational Biology     Hybrid Journal   (Followers: 9)
Journal of Computational Mathematics and Data Science     Open Access  
Journal of Computational Multiphase Flows     Open Access   (Followers: 1)
Journal of Computational Physics     Hybrid Journal   (Followers: 59)
Journal of Computational Physics : X     Open Access   (Followers: 1)
Journal of Computer Engineering, System and Science (CESS)     Open Access  
Journal of Contemporary Mathematical Analysis     Hybrid Journal  
Journal of Cryptology     Hybrid Journal   (Followers: 5)
Journal of Difference Equations and Applications     Hybrid Journal  
Journal of Differential Equations     Full-text available via subscription   (Followers: 1)
Journal of Discrete Mathematics     Open Access   (Followers: 1)
Journal of Dynamics and Differential Equations     Hybrid Journal  
Journal of Engineering Mathematics     Hybrid Journal   (Followers: 2)
Journal of Evolution Equations     Hybrid Journal  
Journal of Experimental Algorithmics     Full-text available via subscription  
Journal of Flood Risk Management     Hybrid Journal   (Followers: 14)
Journal of Function Spaces     Open Access  
Journal of Functional Analysis     Full-text available via subscription   (Followers: 3)
Journal of Geochemical Exploration     Hybrid Journal   (Followers: 4)
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  
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: 3)
Journal of Integrable Systems     Open Access  
Journal of Knot Theory and Its Ramifications     Hybrid Journal   (Followers: 2)
Journal of Liquid Chromatography & Related Technologies     Hybrid Journal   (Followers: 7)
Journal of Logical and Algebraic Methods in Programming     Hybrid Journal   (Followers: 1)
Journal of Manufacturing Systems     Full-text available via subscription   (Followers: 3)
Journal of Mathematical Analysis and Applications     Full-text available via subscription   (Followers: 3)
Journal of mathematical and computational science     Open Access   (Followers: 2)

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Similar Journals
Journal Cover
Graphs and Combinatorics
Journal Prestige (SJR): 0.728
Citation Impact (citeScore): 1
Number of Followers: 4  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1435-5914 - ISSN (Online) 0911-0119
Published by Springer-Verlag Homepage  [2469 journals]
  • H-Kernels by Walks

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      Abstract: Abstract Let \(D=(V,E)\) and \(H=(U,F)\) be digraphs and consider a colouring of the arcs of D with the vertices of H; we say that D is H coloured. We study a natural generalisation of the notion of kernel, as introduced by V. Neumann and Morgenstern (1944), to prove that If every cycle of D is an H-cycle, then D has an H-kernel by walks. As a consequence of this, we are able to give several sufficient conditions for the existence of H-kernels by walks; in particular, we solve partially a conjecture by Bai et al. in this context [2]; viz., they work with complete H without loops, and use paths rather than walks, so whenever the existence of H-paths is implied by the existence of H-walks our result can be use to corroborate Bai’s conjecture—in particular, if D is two coloured, and each cycle is alternating, then each alternating walk contains an alternating path.
      PubDate: 2022-05-16
       
  • Neighbour-Distinguishing Labellings of Families of Graphs

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      Abstract: Abstract A labelling of a graph G is a mapping \(\pi :S \rightarrow {\mathcal {L}}\) , where \({\mathcal {L}}\subset {\mathbb {R}}\) and \(S\in \{E(G), V(G)\cup E(G)\}\) . If \(S=E(G)\) , \(\pi\) is an \({\mathcal {L}}\) -edge-labelling and, if \(S=V(G)\cup E(G)\) , \(\pi\) is an \({\mathcal {L}}\) -total-labelling. For each \(v\in V(G)\) , the colour of v under \(\pi\) is defined as \(c_{\pi }(v) = \sum _{uv \in E(G)}{\pi (uv)}\) if \(\pi\) is an \({\mathcal {L}}\) -edge-labelling; and \(c_{\pi }(v) = \pi (v)+\sum _{uv \in E(G)}{\pi (uv)}\) if \(\pi\) is an \({\mathcal {L}}\) -total-labelling. The pair \((\pi ,c_{\pi })\) is a neighbour-distinguishing \({\mathcal {L}}\) -edge-labelling (neighbour-distinguishing \({\mathcal {L}}\) -total-labelling) if \(\pi\) is an \({\mathcal {L}}\) -edge-labelling ( \({\mathcal {L}}\) -total-labelling) and \(c_{\pi }(u)\ne c_{\pi }(v)\) for every edge \(uv \in E(G)\) . In this work, we show that split graphs, regular cobipartite graphs, complete multipartite graphs and cubic graphs have neighbour-distinguishing \(\{a,b,c\}\) -edge-labellings, for distinct \(a,b,c \in {\mathbb {R}}\) (in some cases \(a,b,c \ge 0\) ). For split graphs and regular cobipartite graphs we also prove they admit neighbour-distinguishing \(\{a,b\}\) -total-labellings. Furthermore, we show that flower snarks and some subfamilies of split graphs and regular cobipartite graphs have neighbour-distinguishing \(\{a,b\}\) -edge-labellings and prove that some families of split graphs do not have neighbour-distinguishing
      PubDate: 2022-05-16
       
  • Neighborhood Complexes, Homotopy Test Graphs and an Application to
           Coloring of Product Graphs

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      Abstract: Abstract The neighborhood complex \(\mathcal {N}(G)\) of a graph G was introduced by L. Lovász in his proof of Kneser conjecture. He proved that for any graph G, 2 $$\begin{aligned} \chi (G) \ge conn(\mathcal {N}(G))+3. \end{aligned}$$ In this article we show that for a class of exponential graphs the bound given in (2) is tight. Further, we show that the neighborhood complexes of these exponential graphs are spheres up to homotopy. We were also able to find a class of exponential graphs, which are homotopy test graphs. In 1966, Hedetniemi conjectured that the chromatic number of the categori-cal product of two graphs is the minimum of the chromatic number of the factors. In 2019, Shitov [26] gave a counterexample to this conjecture. Let M(G) denotes the Mycielskian of a graph G. We show that, for any graph G containing \(M(M(K_n))\) as a subgraph and for any graph H, if \(\chi (G \times H) = n+1\) , then \(\min \{\chi (G), \chi (H)\} = n+1\) . Therefore, we enrich the family of graphs satisfying the Hedetniemi’s conjecture.
      PubDate: 2022-05-13
       
  • Fashion Game on Planar Graphs

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      Abstract: Abstract This paper studies an optimization problem of the fashion game on graphs on surfaces, especially on planar graphs. There are rebel players in a graph G. All players choose their actions from an identical set of the two symmetric actions, say \(\{0,1\}\) . An action profile of G is a mapping \(\pi :V(G)\rightarrow \{0,1\}\) . A rebel likes people having the different action with her and dislikes people having the same action. The utility \(u(v,\pi )\) of a player v under the action profile \(\pi\) is the number of neighbors she likes minus the number of neighbors she dislikes. Let \(\phi :V(G)\rightarrow {\mathbb {Z}}\) be a function. The \(\phi\) -satisfiability problem is to determine whether a graph has an action profile under which each player v has a utility at least \(\phi (v)\) . Let t be an integer. The t-satisfiability problem is the specialized \(\phi\) -satisfiability problem when \(\phi (v)=t\) , for each \(v\in V(G)\) . The utility of G, denoted by u(G), is defined to be the maximum t such that G is t-satisfiable. Let \(\eta : V(G)\rightarrow {\mathbb {N}}\) be a function. A mapping \(c:\ V(G)\rightarrow \{0,1\}\) is called an \(\eta\) -defective 2-coloring of G if every \(v\in V(G)\) has at most \(\eta (v)\) neighbors that have the same color with it. For graphs embeddable in surfaces, upper bounds of their utilities are given. The graphs embeddable in the torus or the Klein bottle whose utilities reach their upper bounds are determined. The t-satisfiability problem for graphs embeddable in the plane, the projective plane, the torus, or the Klein bottle is NP-complete if \(t\in \{1,2,3\}\) , and is polynomial time solvable otherwise. We design a dynamic programming algorithm that solves the \(\phi\) -satisfiability problem for outerplanar graphs in \(O( V(G) ^3)\) time. This algorithm can also solve the \(\eta\) -defective 2-coloring problem for outerplanar graphs.
      PubDate: 2022-05-12
       
  • Equivariant Euler Characteristics of Symplectic Buildings

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      Abstract: Abstract We compute the equivariant Euler characteristics of the buildings for the symplectic groups over finite fields.
      PubDate: 2022-05-11
       
  • On the Unimodality of Domination Polynomials

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      Abstract: Abstract A polynomial is said to be unimodal if its coefficients are non-decreasing and then non-increasing. The domination polynomial of a graph G is the generating function of the number of dominating sets of each cardinality in G, and its coefficients have been conjectured to be unimodal. In this paper we will show the domination polynomial of paths, cycles and complete multipartite graphs are unimodal, and that the domination polynomial of almost every graph is unimodal with mode \( \lceil \frac{n}{2}\rceil \) .
      PubDate: 2022-05-09
       
  • Weakly Distance-Regular Digraphs of One Type of Arcs

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      Abstract: Abstract In this paper, we classify all commutative weakly distance-regular digraphs of girth g and one type of arcs under the assumption that \(p_{(1,g-1),(1,g-1)}^{(2,g-2)}\ge k_{1,g-1}-2\) . In consequence, Yang et al. (J Comb Theory Ser A 160:288–315, 2018, Theorem 1.1) is partially generalized by our result.
      PubDate: 2022-05-04
       
  • On a List Variant of the Multiplicative 1-2-3 Conjecture

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      Abstract: Abstract The 1-2-3 Conjecture asks whether almost all graphs can be (edge-)labelled with 1, 2, 3 so that no two adjacent vertices are incident to the same sum of labels. In the last decades, several aspects of this problem have been studied in literature, including more general versions and slight variations. Notable such variations include the List 1-2-3 Conjecture variant, in which edges must be assigned labels from dedicated lists of three labels, and the Multiplicative 1-2-3 Conjecture variant, in which labels 1, 2, 3 must be assigned to the edges so that adjacent vertices are incident to different products of labels. Several results obtained towards these two variants led to observe some behaviours that are distant from those of the original conjecture. In this work, we consider the list version of the Multiplicative 1-2-3 Conjecture, proposing the first study dedicated to this very problem. In particular, given any graph G, we wonder about the minimum k such that G can be labelled as desired when its edges must be assigned labels from dedicated lists of size k. Exploiting a relationship between our problem and the List 1-2-3 Conjecture, we provide upper bounds on k when G belongs to particular classes of graphs. We further improve some of these bounds through dedicated arguments.
      PubDate: 2022-05-04
       
  • Embedding Grid Graphs on Surfaces

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      Abstract: Abstract In this paper, we analyze embeddings of grid graphs on orientable surfaces. We determine the genus of two infinite classes of 3-dimensional grid graphs that do not admit quadrilateral embeddings and effective upper bounds for the genus of any 3-dimensional grid graph, both in terms of a grid graph’s combinatorics. As an application, we provide a complete classification of planar and toroidal grid graphs. Our work requires a variety of combinatorial and graph theoretic arguments to determine effective lower bounds on the genus of a grid graph, along with explicitly constructing embeddings of grid graphs on surfaces to determine effective upper bounds on their genera.
      PubDate: 2022-04-16
       
  • The Dichromatic Polynomial of a Digraph

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      Abstract: Abstract Let \(\lambda \) be a positive integer. An acyclic \(\lambda \) -coloring of a digraph D is a partition of the vertices of D into \(\lambda \) color clases such that the color classes induce acyclic subdigraphs in D. The minimum integer \(\lambda \) for which there exists an acyclic \(\lambda \) -coloring of D is the dichromatic number dc(D) of D. Let \(P(D;\lambda )\) be the dichromatic polynomial of D, which is the number of acyclic \(\lambda \) -colorings of D. In this paper, a recursive formula for \(P(D;\lambda )\) is given. The coefficients of the polynomial \(P(D;\lambda )\) are studied. The dichromatic polynomial of a digraph D is related to the structure of its underlying graph UG(D). Also, we study dichromatic equivalently and dichromatically unique digraphs.
      PubDate: 2022-04-16
       
  • Greedy Routing in Circulant Networks

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      Abstract: Abstract We address the problem of constructing large circulant networks with given degree and diameter, and efficient routing schemes. First we discuss the theoretical upper bounds and their asymptotics. Then we apply concepts and tools from the change-making problem to efficient routing in circulant graphs. With these tools we investigate some of the families of circulant graphs that have been proposed in the literature, and we construct tables of large circulant graphs and digraphs with efficient routing properties.
      PubDate: 2022-04-16
       
  • The Turán Numbers of Special Forests

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      Abstract: Abstract A graph is called H-free if it does not contain H as a subgraph. The Turán number of H, denoted by ex(n, H), is the maximum number of edges in any H-free graph on n vertices. For sufficiently large n, Lidický et al. (Electron J Combin 20:62, 2013) determined ex(n, F), where F denotes a class of forest with components each of order 4, and they characterized all the extremal graphs. Moreover, Lan et al. (Appl Math Comput 348: 270–274, 2019) proved that the extremal graph is unique when n is large enough. Motivated by their results, we consider a class of forests F with each component a path or star of order 6, we determine ex(n, F) for sufficiently large n and we also characterize all the extremal graphs. Furthermore, we prove that the extremal graph is unique when n is large enough. Let \(kP_n\) denote the disjoint union of k copies of the path \(P_n\) on n vertices. Recently, Lan et al. (Discuss Math Graph Theory 39: 805–814, 2019) determined the exact value of \(ex(n,2P_7)\) . Motivated by their result, we show that \(ex(n,2P_9) = max\{{(7n+153+r(r-8))/2},7n-27\}\) for all \(n\ge 18\) , where r is the remainder of \(n-17\) when divided by 8.
      PubDate: 2022-04-15
       
  • The Rigidity of Infinite Graphs II

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      Abstract: Abstract Inductive constructions are established for countably infinite simple graphs which have minimally rigid locally generic placements in \({{\mathbb{R}}}^2\) . This generalises a well-known result of Henneberg for generically rigid finite graphs. Inductive methods are also employed in the determination of the infinitesimal flexibility dimension of countably infinite graphs associated with infinitely faceted convex polytopes in \({{\mathbb{R}}}^3\) . In particular, a generalisation of Cauchy’s rigidity theorem is obtained.
      PubDate: 2022-04-13
       
  • The Ihara-Zeta Function and the Spectrum of the Join of Two Semi-Regular
           Bipartite Graphs

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      Abstract: Abstract In this paper, using matrix techniques, we compute the Ihara-zeta function and the number of spanning trees of the join of two semi-regular bipartite graphs. Furthermore, we show that the spectrum and the Ihara-zeta function of the join of two semi-regular bipartite graphs can determine each other.
      PubDate: 2022-04-07
       
  • A Note on Exact Minimum Degree Threshold for Fractional Perfect Matchings

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      Abstract: Abstract Rödl, Ruciński, and Szemerédi determined the minimum \((k-1)\) -degree threshold for the existence of fractional perfect matchings in k-uniform hypergrahs, and Kühn, Osthus, and Townsend extended this result by asymptotically determining the d-degree threshold for the range \(k-1>d\ge k/2\) . In this note, we prove the following exact degree threshold: let k, d be positive integers with \(k\ge 4\) and \(k-1>d\ge k/2\) , and let n be any integer with \(n\ge 2k(k-1)+1\) . Then any n-vertex k-uniform hypergraph with minimum d-degree \(\delta _d(H)>{n-d\atopwithdelims ()k-d} -{n-d-(\lceil n/k\rceil -1)\atopwithdelims ()k-d}\) contains a fractional perfect matching. This lower bound on the minimum d-degree is best possible. We also determine the minimum d-degree threshold for the existence of fractional matchings of size s, where \(0<s\le n/k\) (when \(k/2\le d\le k-1\) ), or with s large enough and \(s\le n/k\) (when \(2k/5<d<k/2\) ).
      PubDate: 2022-04-06
       
  • Stability on Matchings in 3-Uniform Hypergraphs

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      Abstract: Abstract Given a positive integer r, let \([r]=\{1,\ldots ,r\}\) . Let n, m be positive integers such that n is sufficiently large and \(1\le m\le \lfloor n/3\rfloor -1\) . Let H be a 3-graph with vertex set [n], and let \(\delta _1(H)\) denote the minimum vertex degree of H. The size of a maximum matching of H is denoted by \(\nu (H)\) . Kühn, Osthus and Treglown (2013) proved that there exists an integer \(n_0\in \mathbb {N}\) such that if H is a 3-graph with \(n\ge n_0\) vertices and \(\delta _1(H)>{n-1\atopwithdelims ()2}-{n-m\atopwithdelims ()2}\) , then \(\nu (H)\ge m\) . In this paper, we show that there exists an integer \(n_1\in \mathbb {N}\) such that if \( V(H) \ge n_1\) , \(\delta _1(H)>{n-1\atopwithdelims ()2}-{n-m\atopwithdelims ()2}+3\) and \(\nu (H)\le m\) , then H is a subgraph of \(H^*(n,m)\) , where \(H^*(n,m)\) is a 3-graph with vertex set [n] and edge set \(E(H^*(n,m))=\{e\subseteq [n]: e =3 \text{ and } e\cap [m] \ne \emptyset \}\) . The minimum degree condition is best possible.
      PubDate: 2022-04-06
       
  • Avoiding and Extending Partial Edge Colorings of Hypercubes

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      Abstract: Abstract We consider the problem of extending and avoiding partial edge colorings of hypercubes; that is, given a partial edge coloring \(\varphi \) of the d-dimensional hypercube \(Q_d\) , we are interested in whether there is a proper d-edge coloring of \(Q_d\) that agrees with the coloring \(\varphi \) on every edge that is colored under \(\varphi \) ; or, similarly, if there is a proper d-edge coloring that disagrees with \(\varphi \) on every edge that is colored under \(\varphi \) . In particular, we prove that for any \(d\ge 1\) , if \(\varphi \) is a partial d-edge coloring of \(Q_d\) , then \(\varphi \) is avoidable if every color appears on at most d/8 edges and the coloring satisfies a relatively mild structural condition, or \(\varphi \) is proper and every color appears on at most \(d-2\) edges. We also show that \(\varphi \) is avoidable if d is divisible by 3 and every color class of \(\varphi \) is an induced matching. Moreover, for all \(1 \le k \le d\) , we characterize for which configurations consisting of a partial coloring \(\varphi \) of \(d-k\) edges and a partial coloring \(\psi \) of k edges, there is an extension of \(\varphi \) that avoids \(\psi \) .
      PubDate: 2022-04-04
       
  • Improved Monochromatic Double Stars in Edge Colorings

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      Abstract: Abstract We give a slight improvement on the size of a monochromatic double star we can guarantee in every r-coloring of the edges of \(K_n\) .
      PubDate: 2022-03-28
       
  • Predominating a Vertex in the Connected Domination Game

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      Abstract: Abstract The connected domination game is played just as the domination game, with an additional requirement that at each stage of the game the vertices played induce a connected subgraph. The number of moves in a D-game (an S-game, resp.) on a graph G when both players play optimally is denoted by \(\gamma _\mathrm{cg}(G)\) ( \(\gamma _\mathrm{cg}'(G)\) , resp.). Connected Game Continuation Principle is established as a substitute for the classical Continuation Principle which does not hold for the connected domination game. Let G x denote the graph G together with a declaration that the vertex x is already dominated. The first main result asserts that if G is a graph with \(\gamma _\mathrm{cg}(G) \ge 3\) and \(x \in V(G)\) , then \(\gamma _\mathrm{cg}(G x) \le 2 \gamma _\mathrm{cg}(G) - 3\) and the bound is sharp. The second main theorem states that if G is a graph with \(n(G) \ge 2\) and \(x \in V(G)\) , then \(\gamma _\mathrm{cg}(G x) \ge \left\lceil \frac{1}{2} \gamma _\mathrm{cg}(G) \right\rceil\) and the bound is sharp. Graphs G and their vertices x for which \(\gamma _\mathrm{cg}'(G x) = \infty\) holds are also characterized.
      PubDate: 2022-03-25
       
  • Improved Bounds on the k-tuple (Roman) Domination Number of a Graph

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      Abstract: Abstract In Henning and Jafari Rad (Graphs Combin, 37: 325–336, 2021), several new probabilistic upper bounds are given on the k-tuple domination number, k-domination number, Roman domination number, and Roman k-domination number of a graph using the well-known Brooks’ Theorem for vertex coloring, improving all of previous given bounds for the above domination variants. In this paper, we use the well-known Turán’s Theorem, and give a slight improvement of all above given bounds.
      PubDate: 2022-03-23
       
 
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