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Wyświetlanie 1-68 z 68
Tytuł:
On a class of functional boundary value problems for the equation x'' = f(t,x,x',x'',λ)
Autorzy:
Staněk, Svatoslav
Powiązania:
https://bibliotekanauki.pl/articles/1311664.pdf
Data publikacji:
1994
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Leray-Schauder degree theory
functional boundary conditions
boundary value problem depending on the parameter
Opis:
The Leray-Schauder degree theory is used to obtain sufficient conditions for the existence and uniqueness of solutions for the boundary value problem x'' = f(t,x,x',x'',λ), α(x) = 0, β(x̅) = 0, γ(x̿)=0, depending on the parameter λ. Here α, β, γ are linear bounded functionals defined on the Banach space of C⁰-functions on [0,1] and x̅(t) = x(0) - x(t), x̿(t)=x(1)-x(t).
Źródło:
Annales Polonici Mathematici; 1994, 59, 3; 225-237
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiplicity of positive solutions for a nonlinear differential equation with nonlinear boundary conditions
Autorzy:
R., D.
Wang, Haiyan
Powiązania:
https://bibliotekanauki.pl/articles/1294312.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
nonlinear boundary value problems
multiplicity of positive solutions
upper and lower solutions
degree theory
Opis:
We study the existence and multiplicity of positive solutions of the nonlinear equation u''(x) + λh(x)f(u(x)) = 0 subject to nonlinear boundary conditions. The method of upper and lower solutions and degree theory arguments are used.
Źródło:
Annales Polonici Mathematici; 1998, 69, 2; 155-165
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fixed point theory for multivalued maps in Fréchet spaces via degree and index theory
Autorzy:
Agarwal, R.
O'Regan, D.
Sahu, D.
Powiązania:
https://bibliotekanauki.pl/articles/729475.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
multivalued maps
Fréchet space
degree and index theory
projective limit
Opis:
New fixed point results are presented for multivalued maps defined on subsets of a Fréchet space E. The proof relies on the notion of a pseudo open set, degree and index theory, and on viewing E as the projective limit of a sequence of Banach spaces.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2007, 27, 2; 399-409
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On some topological methods in theory of neutral type operator differential inclusions with applications to control systems
Autorzy:
Kamenskii, Mikhail
Obukhovskii, Valeri
Yao, Jen-Chih
Powiązania:
https://bibliotekanauki.pl/articles/729536.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
operator differential inclusion
neutral type
periodic solution
fixed point
multivalued map
condensing map
topological degree
averaging method
control system
distributed control
Opis:
We consider a neutral type operator differential inclusion and apply the topological degree theory for condensing multivalued maps to justify the question of existence of its periodic solution. By using the averaging method, we apply the abstract result to an inclusion with a small parameter. As example, we consider a delay control system with the distributed control.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2013, 33, 2; 193-204
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Key moments of the mutual influence of the Polish and Soviet schools of nonlinear functional analysis in the 1920s--1950s
Autorzy:
Bogatov, Egor Mikhailovich
Powiązania:
https://bibliotekanauki.pl/articles/749784.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Polish school of functional analysis, Soviet school of functional analysis, fixed point theorem, Orlicz space, nonlinear integral equations, mapping degree, convex sets, retracts theory
Polska szkoła analizy funkcjonalnej, radziecka szkoła analizy funkcjonalnej, twierdzenie o punkcie stałym, przestrzeń Orlicza, nieliniowe równanie całkowe, stopień odwzorowania, zbiory wypukłe, teoria retraktów
Opis:
Artykuł zawiera kluczowe aspekty historii rozwoju metod jakościowych nieliniowej analizy funkcjonalnej (twierdzenia o punkcie stałym, teoria stopnia odwzorowania, teoria przestrzeni Orlicza), w~ramach których najbardziej uwidoczniły się wzajemne oddziaływania polsko-radzieckie. Do połowy XX wieku w dziedzinach tych  dokonał się  postęp za sprawą  przedstawicieli lwowskiej szkoły matematycznej, warszawskiej szkoły matematycznej, moskiewskiej szkoły matematycznej  i odeskiej szkoły matematycznej. Analiza ich rezultatów stanowi główną część niniejszej pracy. Szczególną uwagę zwracamy na badania matematyka radzieckiego M. A. Krasnosel'skiego, który korzystał z wyników J. Schaudera i K. Borsuka oraz z przestrzeni Orlicza przy rozwiązywaniu szerokiej klasy problemów z jakościowej teorii nieliniowych równań całkowych.
The paper includes key aspects of the history of development of qualitative methods of non-linear functional analysis (fixed point theorems, theory of mapping degree, theory of Orlicz spaces), within the framework of which Polish-Soviet interaction was most clearly manifested. In the period up to the mid-twentieth century these areas were advanced by the representatives of Lvov Mathematical School, Warsaw Mathematical School, Moscow Mathematical School and Odessa Mathematical School. Examination of their results is a significant part of this work. Much attention is paid to the investigations of the Soviet mathematician M.A. Krasnosel'skii, who used the achievements of J. Schauder and K. Borsuk as well as Orlicz spaces for solving a wide class of problems in qualitative theory of nonlinear integral equations. 
Źródło:
Antiquitates Mathematicae; 2017, 11
1898-5203
2353-8813
Pojawia się w:
Antiquitates Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An application of graph theory to linguistic complexity
Autorzy:
Piperski, Alexander
Powiązania:
https://bibliotekanauki.pl/articles/1151871.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
linguistic complexity
morphology
graph theory
average vertex degree
Opis:
This article introduces a new measure of linguistic complexity which is based on the dual nature of the linguistic sign. Complexity is analyzed as consisting of three components, namely the conceptual complexity (complexity of the signified), the formal complexity (complexity of the signifier) and the form-meaning correspondence complexity. I describe a way of plotting the form-meaning relationship on a graph with two tiers (the form tier and the meaning tier) and apply a complexity measure from graph theory (average vertex degree) to assess the complexity of such graphs. The proposed method is illustrated by estimating the complexity of full noun phrases (determiner + adjective + noun) in English, Swedish, and German. I also mention the limitations and the problems which might arise when using this method.
Źródło:
Yearbook of the Poznań Linguistic Meeting; 2014, 1, 1
2449-7525
Pojawia się w:
Yearbook of the Poznań Linguistic Meeting
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An application of graph theory to linguistic complexity
Autorzy:
Piperski, Alexander
Powiązania:
https://bibliotekanauki.pl/articles/2135360.pdf
Data publikacji:
2014-11-19
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
linguistic complexity
morphology
graph theory
average vertex degree
Opis:
This article introduces a new measure of linguistic complexity which is based on the dual nature of the linguistic sign. Complexity is analyzed as consisting of three components, namely the conceptual complexity (complexity of the signified), the formal complexity (complexity of the signifier) and the form-meaning correspondence complexity. I describe a way of plotting the form-meaning relationship on a graph with two tiers (the form tier and the meaning tier) and apply a complexity measure from graph theory (average vertex degree) to assess the complexity of such graphs. The proposed method is illustrated by estimating the complexity of full noun phrases (determiner + adjective + noun) in English, Swedish, and German. I also mention the limitations and the problems which might arise when using this method.
Źródło:
Yearbook of the Poznań Linguistic Meeting; 2014, 1, 1; 89-102
2449-7525
Pojawia się w:
Yearbook of the Poznań Linguistic Meeting
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acyclic 6-Colouring of Graphs with Maximum Degree 5 and Small Maximum Average Degree
Autorzy:
Fiedorowicz, Anna
Powiązania:
https://bibliotekanauki.pl/articles/30146851.pdf
Data publikacji:
2013-03-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
acyclic colouring
bounded degree graph
maximum average degree
Opis:
A k-colouring of a graph G is a mapping c from the set of vertices of G to the set {1, . . ., k} of colours such that adjacent vertices receive distinct colours. Such a k-colouring is called acyclic, if for every two distinct colours i and j, the subgraph induced by all the edges linking a vertex coloured with i and a vertex coloured with j is acyclic. In other words, every cycle in G has at least three distinct colours. Acyclic colourings were introduced by Gr¨unbaum in 1973, and since then have been widely studied. In particular, the problem of acyclic colourings of graphs with bounded maximum degree has been investigated. In 2011, Kostochka and Stocker showed that any graph with maximum degree 5 can be acyclically coloured with at most 7 colours. The question, whether this bound is achieved, remains open. In this note we prove that any graph with maximum degree 5 and maximum average degree at most 4 admits an acyclic 6-colouring. We also provide examples of graphs with these properties.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 1; 91-99
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Degree-Diameter Problem for Outerplanar Graphs
Autorzy:
Dankelmann, Peter
Jonck, Elizabeth
Vetrík, Tomáš
Powiązania:
https://bibliotekanauki.pl/articles/31341627.pdf
Data publikacji:
2017-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
outerplanar
diameter
degree
degree-diameter problem
distance
separator theorem
Opis:
For positive integers $ \Delta $ and $ D $ we define $ n_{ \Delta, D } $ to be the largest number of vertices in an outerplanar graph of given maximum degree $ \Delta $ and diameter $D$. We prove that $n_{ \Delta , D} = \Delta^{D/2} + O ( \Delta^{ D/2 -1 } ) $ if $D$ is even, and $ n_{ \Delta, D} = 3 \Delta^\frac{D−1}{2} + O (\Delta^{ \frac{D−1}{2}−1 } ) $ if $D$ is odd. We then extend our result to maximal outerplanar graphs by showing that the maximum number of vertices in a maximal outerplanar graph of maximum degree $ \Delta $ and diameter $D$ asymptotically equals$ n_{ \Delta , D }.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 3; 823-834
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degree sequences of monocore graphs
Autorzy:
Bickle, Allan
Powiązania:
https://bibliotekanauki.pl/articles/30148681.pdf
Data publikacji:
2014-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
monocore graph
degeneracy
degree sequence
Opis:
A $k$-monocore graph is a graph which has its minimum degree and degeneracy both equal to $k$. Integer sequences that can be the degree sequence of some $k$-monocore graph are characterized as follows. A nonincreasing sequence of integers $d_1, . . ., d_n$ is the degree sequence of some $k$-monocore graph $G, 0 ≤ k ≤ n − 1$, if and only if $k ≤ di ≤ min {n − 1, k + n − i}$ and $⨊d_i = 2m$, where $m$ satisfies $$\lceil\frac{k·n}{2}\rceil ≤ m ≤ k ・ n − \binom{k+1}{2}$$
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 3; 585-592
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An implicit weighted degree condition for heavy cycles
Autorzy:
Cai, Junqing
Li, Hao
Ning, Wantao
Powiązania:
https://bibliotekanauki.pl/articles/30148719.pdf
Data publikacji:
2014-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
weighted graph
hamiltonian cycles
heavy cycles
implicit degree
implicit weighted degree
Opis:
For a vertex v in a weighted graph G, idw(v) denotes the implicit weighted degree of v. In this paper, we obtain the following result: Let G be a 2-connected weighted graph which satisfies the following conditions: (a) The implicit weighted degree sum of any three independent vertices is at least t; (b) w(xz) = w(yz) for every vertex z ∈ N(x) ∩ N(y) with xy /∈ E(G); (c) In every triangle T of G, either all edges of T have different weights or all edges of T have the same weight. Then G contains either a hamiltonian cycle or a cycle of weight at least 2t/3. This generalizes the result of Zhang et al. [9].
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 4; 801-810
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On a Spanning $k$-Tree in which Specified Vertices Have Degree Less Than $k$
Autorzy:
Matsumura, Hajime
Powiązania:
https://bibliotekanauki.pl/articles/31339152.pdf
Data publikacji:
2015-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spanning tree
degree bounded tree
degree sum condition
Opis:
A $k$-tree is a tree with maximum degree at most $k$. In this paper, we give a degree sum condition for a graph to have a spanning $k$-tree in which specified vertices have degree less than $k$. We denote by $\sigma_k(G)$ the minimum value of the degree sum of $k$ independent vertices in a graph $G$. Let $k ≥ 3$ and s $≥ 0$ be integers, and suppose $G$ is a connected graph and $\sigma_k(G) ≥ |V (G)|+s−1$. Then for any $s$ specified vertices, $G$ contains a spanning $k$-tree in which every specified vertex has degree less than $k$. The degree condition is sharp.
Źródło:
Discussiones Mathematicae Graph Theory; 2015, 35, 1; 191-196
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
3-Paths in Graphs with Bounded Average Degree
Autorzy:
Jendrol, Stanislav
Maceková, Mária
Montassier, Mickaël
Soták, Roman
Powiązania:
https://bibliotekanauki.pl/articles/31340952.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
average degree
structural property
3-path
degree sequence
Opis:
In this paper we study the existence of unavoidable paths on three vertices in sparse graphs. A path uvw on three vertices u, v, and w is of type (i, j, k) if the degree of u (respectively v, w) is at most i (respectively j, k). We prove that every graph with minimum degree at least 2 and average degree strictly less than m contains a path of one of the types Moreover, no parameter of this description can be improved.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 339-353
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Smallest Regular Graphs of Given Degree and Diameter
Autorzy:
Knor, Martin
Powiązania:
https://bibliotekanauki.pl/articles/30147224.pdf
Data publikacji:
2014-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
regular graph
degree/diameter problem
extremal graph
Opis:
In this note we present a sharp lower bound on the number of vertices in a regular graph of given degree and diameter.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 1; 187-191
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vertex-disjoint copies of K¯₄
Autorzy:
Kawarabayashi, Ken-ichi
Powiązania:
https://bibliotekanauki.pl/articles/744487.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
extremal graph theory
vertex disjoint copy
minimum degree
Opis:
Let G be a graph of order n. Let K¯ₗ be the graph obtained from Kₗ by removing one edge.
In this paper, we propose the following conjecture:
Let G be a graph of order n ≥ lk with δ(G) ≥ (n-k+1)(l-3)/(l-2)+k-1. Then G has k vertex-disjoint K¯ₗ.
This conjecture is motivated by Hajnal and Szemerédi's [6] famous theorem. In this paper, we verify this conjecture for l=4.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 2; 249-262
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On degree sets and the minimum orders in bipartite graphs
Autorzy:
Manoussakis, Y.
Patil, H.P.
Powiązania:
https://bibliotekanauki.pl/articles/30148239.pdf
Data publikacji:
2014-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
degree sets
unicyclic graphs
Opis:
For any simple graph G, let D(G) denote the degree set ${deg_G(v) : v ∈ V (G)}$. Let S be a finite, nonempty set of positive integers. In this paper, we first determine the families of graphs G which are unicyclic, bipartite satisfying D(G) = S, and further obtain the graphs of minimum orders in such families. More general, for a given pair (S, T) of finite, nonempty sets of positive integers of the same cardinality, it is shown that there exists a bipartite graph B(X, Y) such that D(X) = S, D(Y ) = T and the minimum orders of different types are obtained for such graphs
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 2; 383-390
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Families of triples with high minimum degree are Hamiltonian
Autorzy:
Rödl, Vojtech
Ruciński, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/30148238.pdf
Data publikacji:
2014-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
3-uniform hypergraph
Hamilton cycle
minimum vertex degree
Opis:
In this paper we show that every family of triples, that is, a 3-uniform hypergraph, with minimum degree at least $$(\frac{5−√5}{3} + γ)\binom{n−1}{2}$$ contains a tight Hamiltonian cycle.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 2; 361-381
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Equitable Coloring and Equitable Choosability of Graphs with Small Maximum Average Degree
Autorzy:
Dong, Aijun
Zhang, Xin
Powiązania:
https://bibliotekanauki.pl/articles/31342275.pdf
Data publikacji:
2018-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph coloring
equitable choosability
maximum average degree
Opis:
A graph is said to be equitably $k$-colorable if the vertex set $V (G)$ can be partitioned into $k$ independent subsets $ V_1, V_2, . . ., V_k $ such that $ | | V_i |−| V_j | | \le 1 $ $(1 \le i, j \le k) $. A graph $G$ is equitably $k$-choosable if, for any given $k$-uniform list assignment $L$, $G$ is $L$-colorable and each color appears on at most $ \ceil{ \frac{|V(G)|}{ k } } $ vertices. In this paper, we prove that if $G$ is a graph such that $ mad(G) < 3 $, then $G$ is equitably $k$-colorable and equitably $k$- choosable where $ k \ge \text{max} \{ \Delta (G), 4 \} $. Moreover, if $G$ is a graph such that $ mad(G) < \frac{12}{5} $, then $G$ is equitably $k$-colorable and equitably $k$-choosable where $ k \ge \text{max} \{ \Delta (G), 3 \} $.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 3; 829-839
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some applications of pq-groups in graph theory
Autorzy:
Exoo, Geoffrey
Powiązania:
https://bibliotekanauki.pl/articles/744429.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Ramsey number
edge coloring
cage
degree
girth
Cayley graph
Opis:
We describe some new applications of nonabelian pq-groups to construction problems in Graph Theory. The constructions include the smallest known trivalent graph of girth 17, the smallest known regular graphs of girth five for several degrees, along with four edge colorings of complete graphs that improve lower bounds on classical Ramsey numbers.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 1; 109-114
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Large Degree Vertices in Longest Cycles of Graphs, I
Autorzy:
Li, Binlong
Xiong, Liming
Yin, Jun
Powiązania:
https://bibliotekanauki.pl/articles/31340944.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
longest cycle
large degree vertices
order
connectivity
independent number
Opis:
In this paper, we consider the least integer d such that every longest cycle of a k-connected graph of order n (and of independent number α) contains all vertices of degree at least d.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 363-382
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Distance Spectral Radius of Trees with Given Degree Sequence
Autorzy:
Dadedzi, Kenneth
Misanantenaina, Valisoa Razanajatovo
Wagner, Stephan
Powiązania:
https://bibliotekanauki.pl/articles/31548271.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance matrix
spectral radius
tree
degree sequence
Opis:
We consider the problem of maximizing the distance spectral radius and a slight generalization thereof among all trees with some prescribed degree sequence. We prove in particular that the maximum of the distance spectral radius has to be attained by a caterpillar for any given degree sequence. The same holds true for the terminal distance matrix. Moreover, we consider a generalized version of the reverse distance matrix and also study its spectral radius for trees with given degree sequence. We prove that the spectral radius is always maximized by a greedy tree. This implies several corollaries, among them a “reversed” version of a conjecture of Stevanović and Ilić. Our results parallel similar theorems for the Wiener index and other invariants.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 495-524
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2-Connected Hamiltonian Claw-Free Graphs Involving Degree Sum of Adjacent Vertices
Autorzy:
Tian, Tao
Xiong, Liming
Powiązania:
https://bibliotekanauki.pl/articles/32034090.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Hamiltonian cycle
degree sum
dominating closed trail
closure
Opis:
For a graph H, define $\overline{\sigma}_2(H)=min\{d(u)+d(v)|uv∈E(H)\}$. Let $H$ be a 2-connected claw-free simple graph of order $n$ with \(\delta(H) ≥ 3\). In [J. Graph Theory 86 (2017) 193–212], Chen proved that if $\overline{\sigma}_2(H)≥\frac{n}{2}−1$ and $n$ is sufficiently large, then $H$ is Hamiltonian with two families of exceptions. In this paper, we refine the result. We focus on the condition $\overline{\sigma}_2(H)≥\frac{2n}{5}−1$, and characterize non-Hamiltonian 2-connected claw-free graphs $H$ of order $n$ sufficiently large with $\overline{\sigma}_2(H)≥\frac{2n}{5}−1$. As byproducts, we prove that there are exactly six graphs in the family of 2-edge-connected triangle-free graphs of order at most seven that have no spanning closed trail and give an improvement of a result of Veldman in [Discrete Math. 124 (1994) 229–239].
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 85-106
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Super Edge-Connectivity and Zeroth-Order Randić Index
Autorzy:
He, Zhihong
Lu, Mei
Powiązania:
https://bibliotekanauki.pl/articles/31348172.pdf
Data publikacji:
2020-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
zeroth-order Randić index
super edge-connected
degree
triangle-free graph
minimum degree
Opis:
Define the zeroth-order Randić index as \(R^0(G)=∑_{x∈V(G)} \frac{1}{\sqrt{d_G(x)}}\), where $d_G(x)$ denotes the degree of the vertex $x$. In this paper, we present two sufficient conditions for graphs and triangle-free graphs, respectively, to be super edge-connected in terms of the zeroth-order Randić index.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 4; 971-984
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Degree Condition Implying Ore-Type Condition for Even [2, b]-Factors in Graphs
Autorzy:
Tsuchiya, Shoichi
Yashima, Takamasa
Powiązania:
https://bibliotekanauki.pl/articles/31341635.pdf
Data publikacji:
2017-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
[ a, b ]-factor
even factor
2-edge-connected
minimum degree
Opis:
For a graph $G$ and even integers $ b \ge a \ge 2 $, a spanning subgraph $F$ of $G$ such that $ a \le \text{deg}_F (x) \le b $ and $ \text{deg}_F (x) $ is even for all $ x \in V (F) $ is called an even $[a, b]$-factor of $G$. In this paper, we show that a 2-edge-connected graph $G$ of order $n$ has an even $[2, b]$-factor if $ \text{max} \{ \text{deg}_G (x) , \text{deg}_G (y) \} \ge \text{max} \{ \frac{2n}{2+b} , 3 \} $ for any nonadjacent vertices $x$ and $y$ of $G$. Moreover, we show that for $ b \ge 3a$ and $a > 2$, there exists an infinite family of 2-edge-connected graphs $G$ of order $n$ with $ \delta (G) \ge a$ such that $G$ satisfies the condition $ \text{deg}_G (x) + \text{deg}_G (y) > \frac{2an}{a+b} $ for any nonadjacent vertices $x$ and $y$ of $G$, but has no even $[a, b]$-factors. In particular, the infinite family of graphs gives a counterexample to the conjecture of Matsuda on the existence of an even $[a, b]$-factor.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 3; 797-809
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
5-stars of low weight in normal plane maps with minimum degree 5
Autorzy:
Borodin, Oleg V.
Ivanova, Anna O.
Jensen, Tommy R.
Powiązania:
https://bibliotekanauki.pl/articles/30148303.pdf
Data publikacji:
2014-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
plane map
vertex degree
weight
light subgraph
Opis:
It is known that there are normal plane maps $M_5$ with minimum degree 5 such that the minimum degree-sum $w(S_5)$ of 5-stars at 5-vertices is arbitrarily large. In 1940, Lebesgue showed that if an $M_5$ has no 4-stars of cyclic type (5, 6, 6, 5) centered at 5-vertices, then $w(S_5) ≤ 68$. We improve this bound of 68 to 55 and give a construction of a (5, 6, 6, 5)-free $M_5$ with $w(S_5) = 48$.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 3; 539-546
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nordhaus-Gaddum-Type Results for Resistance Distance-Based Graph Invariants
Autorzy:
Das, Kinkar Ch.
Yang, Yujun
Xu, Kexiang
Powiązania:
https://bibliotekanauki.pl/articles/31340811.pdf
Data publikacji:
2016-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
resistance distance
Kirchhoff index
additive degree-Kirchhoff index
multiplicative degree-Kirchhoff index
Nordhaus-Gaddum-type result
Opis:
Two decades ago, resistance distance was introduced to characterize “chemical distance” in (molecular) graphs. In this paper, we consider three resistance distance-based graph invariants, namely, the Kirchhoff index, the additive degree-Kirchhoff index, and the multiplicative degree-Kirchhoff index. Some Nordhaus-Gaddum-type results for these three molecular structure descriptors are obtained. In addition, a relation between these Kirchhoffian indices is established.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 3; 695-707
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Supermagic Generalized Double Graphs
Autorzy:
Ivančo, Jaroslav
Powiązania:
https://bibliotekanauki.pl/articles/31341097.pdf
Data publikacji:
2016-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
double graphs
supermagic graphs
degree-magic graphs
Opis:
A graph G is called supermagic if it admits a labelling of the edges by pairwise di erent consecutive integers such that the sum of the labels of the edges incident with a vertex is independent of the particular vertex. In this paper we will introduce some constructions of supermagic labellings of some graphs generalizing double graphs. Inter alia we show that the double graphs of regular Hamiltonian graphs and some circulant graphs are supermagic.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 1; 211-225
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degree Sum Condition for the Existence of Spanning k-Trees in Star-Free Graphs
Autorzy:
Furuya, Michitaka
Maezawa, Shun-ichi
Matsubara, Ryota
Matsuda, Haruhide
Tsuchiya, Shoichi
Yashima, Takamasa
Powiązania:
https://bibliotekanauki.pl/articles/32361756.pdf
Data publikacji:
2022-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spanning tree
k -tree
star-free
degree sum condition
Opis:
For an integer k ≥ 2, a k-tree T is defined as a tree with maximum degree at most k. If a k-tree T spans a graph G, then T is called a spanning k-tree of G. Since a spanning 2-tree is a Hamiltonian path, a spanning k-tree is an extended concept of a Hamiltonian path. The first result, implying the existence of k-trees in star-free graphs, was by Caro, Krasikov, and Roditty in 1985, and independently, Jackson and Wormald in 1990, who proved that for any integer k with k ≥ 3, every connected K1,k-free graph contains a spanning k-tree. In this paper, we focus on a sharp condition that guarantees the existence of a spanning k-tree in K1,k+1-free graphs. In particular, we show that every connected K1,k+1-free graph G has a spanning k-tree if the degree sum of any 3k−3 independent vertices in G is at least |G|−2, where |G| is the order of G.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 1; 5-13
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A different short proof of Brooks theorem
Autorzy:
Rabern, Landon
Powiązania:
https://bibliotekanauki.pl/articles/31231996.pdf
Data publikacji:
2014-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
coloring
clique number
maximum degree
Opis:
Lovász gave a short proof of Brooks’ theorem by coloring greedily in a good order. We give a different short proof by reducing to the cubic case.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 3; 633-634
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Domination Number of Graphs with Minimum Degree Five
Autorzy:
Bujtás, Csilla
Powiązania:
https://bibliotekanauki.pl/articles/32222697.pdf
Data publikacji:
2021-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
dominating set
domination number
discharging method
Opis:
We prove that for every graph G on n vertices and with minimum degree five, the domination number γ(G) cannot exceed n/3. The proof combines an algorithmic approach and the discharging method. Using the same technique, we provide a shorter proof for the known upper bound 4n/11 on the domination number of graphs of minimum degree four.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 3; 763-777
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Factorable Bigraphic Pairs
Autorzy:
Yin, Jian-Hua
Li, Sha-Sha
Powiązania:
https://bibliotekanauki.pl/articles/31515537.pdf
Data publikacji:
2020-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
degree sequence
bigraphic pair
Hamiltonian cycle
Opis:
Let $S = (a_1,. . ., a_m; b_1, . . ., b_n)$, where $a_1, . . ., a_m$ and $b_1, . . ., b_n$ are two sequences of nonnegative integers. We say that $S$ is a bigraphic pair if there exists a simple bipartite graph $G$ with partite sets ${x_1, x_2, . . ., x_m}$ and ${y_1, y_2, . . ., y_n}$ such that $d_G(x_i) = a_i$ for $1 ≤ i ≤ m$ and $d_G(y_j) = b_j$ for $1 ≤ j ≤ n$. In this case, we say that $G$ is a realization of $S$. Analogous to Kundu’s $k$-factor theorem, we show that if $(a_1, a_2, . . ., a_m; b_1, b_2, . . ., b_n)$ and $(a_1 − e_1, a_2 − e_2, . . ., a_m − e_m; b_1 − f_1, b_2 − f_2, . . ., b_n − f_n)$ are two bigraphic pairs satisfying $k ≤ f_i ≤ k + 1, 1 ≤ i ≤ n$ (or$ k ≤ e_i ≤ k + 1, 1 ≤ i ≤ m$), for some $0 ≤ k ≤ m − 1$ (or $0 ≤ k ≤ n − 1$), then $(a_1, a_2, . . ., a_m; b_1, b_2, . . ., b_n)$ has a realization containing an $(e_1, e_2, . . ., e_m; f_1, f_2, . . ., f_n)$-factor. For $m = n$, we also give a necessary and sufficient condition for an $(k^n; k^n)$-factorable bigraphic pair to be connected $(k^n; k^n)$-factorable when $k ≥ 2$. This implies a characterization of bigraphic pairs with a realization containing a Hamiltonian cycle.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 3; 787-793
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Describing Minor 5-Stars in 3-Polytopes with Minimum Degree 5 and No Vertices of Degree 6 or 7
Autorzy:
Batueva, Ts.Ch-D.
Borodin, O.V.
Ivanova, A.O.
Nikiforov, D.V.
Powiązania:
https://bibliotekanauki.pl/articles/32361718.pdf
Data publikacji:
2022-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar graph
structural properties
3-polytope
5-star
neighborhood
Opis:
In 1940, in attempts to solve the Four Color Problem, Henry Lebesgue gave an approximate description of the neighborhoods of 5-vertices in the class P5 of 3-polytopes with minimum degree 5. This description depends on 32 main parameters. (6, 6, 7, 7, 7), (6, 6, 6, 7, 9), (6, 6, 6, 6, 11), (5, 6, 7, 7, 8), (5, 6, 6, 7, 12), (5, 6, 6, 8, 10), (5, 6, 6, 6, 17), (5, 5, 7, 7, 13), (5, 5, 7, 8, 10), (5, 5, 6, 7, 27), (5, 5, 6, 6, ∞), (5, 5, 6, 8, 15), (5, 5, 6, 9, 11), (5, 5, 5, 7, 41), (5, 5, 5, 8, 23), (5, 5, 5, 9, 17), (5, 5, 5, 10, 14), (5, 5, 5, 11, 13) Not many precise upper bounds on these parameters have been obtained as yet, even for restricted subclasses in P5. In 2018, Borodin, Ivanova, Kazak proved that every forbidding vertices of degree from 7 to 11 results in a tight description (5, 5, 6, 6, ∞), (5, 6, 6, 6, 15), (6, 6, 6, 6, 6). Recently, Borodin, Ivanova, and Kazak proved every 3-polytope in P5 with no vertices of degrees 6, 7, and 8 has a 5-vertex whose neighborhood is majorized by one of the sequences (5, 5, 5, 5, ∞) and (5, 5, 10, 5, 12), which is tight and improves a corresponding description (5, 5, 5, 5, ∞), (5, 5, 9, 5, 17), (5, 5, 10, 5, 14), (5, 5, 11, 5, 13) that follows from the Lebesgue Theorem. The purpose of this paper is to prove that every 3-polytope with minimum degree 5 and no vertices of degree 6 or 7 has a 5-vertex whose neighborhood is majorized by one of the ordered sequences (5, 5, 5, 5, ∞), (5, 5, 8, 5, 14), or (5, 5, 10, 5, 12).
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 2; 535-548
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Saturation Number for the Length of Degree Monotone Paths
Autorzy:
Caro, Yair
Lauri, Josef
Zarb, Christina
Powiązania:
https://bibliotekanauki.pl/articles/31339330.pdf
Data publikacji:
2015-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
paths
degrees
saturation
Opis:
A degree monotone path in a graph G is a path P such that the sequence of degrees of the vertices in the order in which they appear on P is monotonic. The length (number of vertices) of the longest degree monotone path in G is denoted by mp(G). This parameter, inspired by the well-known Erdős- Szekeres theorem, has been studied by the authors in two earlier papers. Here we consider a saturation problem for the parameter mp(G). We call G saturated if, for every edge e added to G, mp(G + e) > mp(G), and we define h(n, k) to be the least possible number of edges in a saturated graph G on n vertices with mp(G) < k, while mp(G+e) ≥ k for every new edge e. We obtain linear lower and upper bounds for h(n, k), we determine exactly the values of h(n, k) for k = 3 and 4, and we present constructions of saturated graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2015, 35, 3; 557-569
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Hypercompetition Numbers of Hypergraphs with Maximum Degree at Most Two
Autorzy:
Sano, Yoshio
Powiązania:
https://bibliotekanauki.pl/articles/31339316.pdf
Data publikacji:
2015-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
digraph
competition hypergraph
hypercompetition number
Opis:
In this note, we give an easy and short proof for the theorem by Park and Kim stating that the hypercompetition numbers of hypergraphs with maximum degree at most two is at most two.
Źródło:
Discussiones Mathematicae Graph Theory; 2015, 35, 3; 595-598
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Smallest Harmonic Index of Trees with Given Maximum Degree
Autorzy:
Rasi, Reza
Sheikholeslami, Seyed Mahmoud
Powiązania:
https://bibliotekanauki.pl/articles/31342320.pdf
Data publikacji:
2018-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
harmonic index
trees
Opis:
The harmonic index of a graph G, denoted by H(G), is defined as the sum of weights 2/[d(u) + d(v)] over all edges uv of G, where d(u) denotes the degree of a vertex u. In this paper we establish a lower bound on the harmonic index of a tree T.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 2; 499-513
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Homotopy Approach to Rational Covariance Extension With Degree Constraint
Autorzy:
Enqvist, P.
Powiązania:
https://bibliotekanauki.pl/articles/908061.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
optymalizacja
teoria systemów
stochastic realization theory
rational covariance extension problem
ARMA model design
continuation method
optimization
Opis:
The solutions to the Rational Covariance Extension Problem (RCEP) are parameterized by the spectral zeros. The rational filter with a specified numerator solving the RCEP can be determined from a known convex optimization problem. However, this optimization problem may become ill-conditioned for some parameter values. A modification of the optimization problem to avoid the ill-conditioning is proposed and the modified problem is solved efficiently by a continuation method.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2001, 11, 5; 1173-1201
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low 5-Stars at 5-Vertices in 3-Polytopes with Minimum Degree 5 and No Vertices of Degree from 7 to 9
Autorzy:
Borodin, Oleg V.
Bykov, Mikhail A.
Ivanova, Anna O.
Powiązania:
https://bibliotekanauki.pl/articles/31348144.pdf
Data publikacji:
2020-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar map
planar graph
3-polytope
structural properties
5-star
weight
height
Opis:
In 1940, Lebesgue gave an approximate description of the neighborhoods of 5-vertices in the class $P_5$ of 3-polytopes with minimum degree 5. Given a 3-polytope $P$, by $h_5(P)$ we denote the minimum of the maximum degrees (height) of the neighborhoods of 5-vertices (minor 5-stars) in $P$. Recently, Borodin, Ivanova and Jensen showed that if a polytope $P$ in $P_5$ is allowed to have a 5-vertex adjacent to two 5-vertices and two more vertices of degree at most 6, called a (5, 5, 6, 6, ∞)-vertex, then $h_5(P)$ can be arbitrarily large. Therefore, we consider the subclass \(P_5^\ast\) of 3-polytopes in $P_5$ that avoid (5, 5, 6, 6, ∞)-vertices. For each $P^\ast$ in $P_5^\ast$ without vertices of degree from 7 to 9, it follows from Lebesgue’s Theorem that $h_5(P^\ast) ≤ 17$. Recently, this bound was lowered by Borodin, Ivanova, and Kazak to the sharp bound $h_5(P^\ast) ≤ 15$ assuming the absence of vertices of degree from 7 to 11 in $P^\ast$. In this note, we extend the bound $h_5(P^\ast) ≤ 15$ to all $P^\ast$s without vertices of degree from 7 to 9.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 4; 1025-1033
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Rainbow Vertex-Connection
Autorzy:
Li, Xueliang
Shi, Yongtang
Powiązania:
https://bibliotekanauki.pl/articles/30146636.pdf
Data publikacji:
2013-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
rainbow vertex-connection
vertex coloring
minimum degree
2-step dominating set
Opis:
A vertex-colored graph is rainbow vertex-connected if any two vertices are connected by a path whose internal vertices have distinct colors. The rainbow vertex-connection of a connected graph $G$, denoted by $rvc(G)$, is the smallest number of colors that are needed in order to make $G$ rainbow vertex-connected. It was proved that if $G$ is a graph of order $n$ with minimum degree $ \delta $, then $ rvc(G) < 11n//\delta$. In this paper, we show that $rvc(G) \le 3n//(δ+1)+5$ for $ \delta \ge \sqrt{n-1} -1 $ and $ n \le 290 $, while $ rvc(G) \le 4n//(δ + 1) + 5 $ for $ 16 \le \delta \le \sqrt{n-1}-2 $ and $ rvc(G) \le 4n//(\delta + 1) + C(\delta) $ for $6 \le \delta \le 15$, where $ C(\delta) = e^\frac{ 3 \log (\delta^3 + 2 \delta^2 +3)-3(\log 3 - 1)}{\delta - 3} - 2$. We also prove that $ rvc(G) \le 3n//4 − 2 $ for $ \delta = 3$, $ rvc(G) \le 3n//5 − 8//5$ for $\delta = 4$ and $rvc(G) \le n//2 − 2$ for $\delta = 5$. Moreover, an example constructed by Caro et al. shows that when $ \delta \ge \sqrt{n-1} - 1 $ and $ \delta = 3, 4, 5 $, our bounds are seen to be tight up to additive constants.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 2; 307-313
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trees Whose Even-Degree Vertices Induce a Path are Antimagic
Autorzy:
Lozano, Antoni
Mora, Mercè
Seara, Carlos
Tey, Joaquín
Powiązania:
https://bibliotekanauki.pl/articles/32304141.pdf
Data publikacji:
2022-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
antimagic labeling
tree
Opis:
An antimagic labeling of a connected graph G is a bijection from the set of edges E(G) to {1, 2, . . ., |E(G)|} such that all vertex sums are pairwise distinct, where the vertex sum at vertex v is the sum of the labels assigned to edges incident to v. A graph is called antimagic if it has an antimagic labeling. In 1990, Hartsfield and Ringel conjectured that every simple connected graph other than K2 is antimagic; however the conjecture remains open, even for trees. In this note we prove that trees whose vertices of even degree induce a path are antimagic, extending a result given by Liang, Wong, and Zhu [Anti-magic labeling of trees, Discrete Math. 331 (2014) 9–14].
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 3; 959-966
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Linear List Coloring of Some Sparse Graphs
Autorzy:
Chen, Ming
Li, Yusheng
Zhang, Li
Powiązania:
https://bibliotekanauki.pl/articles/32083756.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
linear coloring
maximum average degree
planar graphs
discharging
Opis:
A linear $k$-coloring of a graph is a proper $k$-coloring of the graph such that any subgraph induced by the vertices of any pair of color classes is a union of vertex-disjoint paths. A graph $G$ is linearly $L$-colorable if there is a linear coloring $c$ of $G$ for a given list assignment $L = \{L(v) : v ∈ V(G)\}$ such that $c(v) ∈ L(v)$ for all $v ∈ V(G)$, and $G$ is linearly $k$-choosable if $G$ is linearly $L$-colorable for any list assignment with $|L(v)| ≥ k$. The smallest integer $k$ such that $G$ is linearly $k$-choosable is called the linear list chromatic number, denoted by $lc_l(G)$. It is clear that \(lc_l(G)≥\Big\lceil\frac{\Delta(G)}{1}\Big\rceil+1\) for any graph $G$ with maximum degree $\Delta(G)$. The maximum average degree of a graph $G$, denoted by $mad(G)$, is the maximum of the average degrees of all subgraphs of $G$. In this note, we shall prove the following. Let $G$ be a graph, (1) if $mad(G)<\frac{8}{3}$ and $\Delta(G) ≥ 7$, then \(lc_l(G)=\Big\lceil\frac{\Delta(G)}{2}\Big\rceil+1\); (2) if $mad(G)<{18}{7}$ and $\Delta(G) ≥ 5$, then \(lc_l(G)=\Big\lceil\frac{\Delta(G)}{2}\Big\rceil+1\); (3) if $mad(G)<{20}{7}$ and $\Delta(G) ≥ 5$, then \(lc_l(G)≤\Big\lceil\frac{\Delta(G)}{2}\Big\rceil+2\).
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 51-64
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Bipartite-Splittance of a Bipartite Graph
Autorzy:
Yin, Jian-Hua
Guan, Jing-Xin
Powiązania:
https://bibliotekanauki.pl/articles/31343732.pdf
Data publikacji:
2019-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
degree sequence pair
bipartite-split graph
bipartite-splittance
Opis:
A bipartite-split graph is a bipartite graph whose vertex set can be partitioned into a complete bipartite set and an independent set. The bipartite- splittance of an arbitrary bipartite graph is the minimum number of edges to be added or removed in order to produce a bipartite-split graph. In this paper, we show that the bipartite-splittance of a bipartite graph depends only on the degree sequence pair of the bipartite graph, and an easily computable formula for it is derived. As a corollary, a simple characterization of the degree sequence pair of bipartite-split graphs is also given.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 1; 23-29
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Eccentricity of Networks with Structural Constraints
Autorzy:
Krnc, Matjaž
Sereni, Jean-Sébastien
Škrekovski, Riste
Yilma, Zelealem B.
Powiązania:
https://bibliotekanauki.pl/articles/31348091.pdf
Data publikacji:
2020-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
eccentricity
network
bipartite graph
complex network
maximum degree
Opis:
The eccentricity of a node v in a network is the maximum distance from v to any other node. In social networks, the reciprocal of eccentricity is used as a measure of the importance of a node within a network. The associated centralization measure then calculates the degree to which a network is dominated by a particular node. In this work, we determine the maximum value of eccentricity centralization as well as the most centralized networks for various classes of networks including the families of bipartite networks (two-mode data) with given partition sizes and tree networks with fixed number of nodes and fixed maximum degree. To this end, we introduce and study a new way of enumerating the nodes of a tree which might be of independent interest.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 4; 1141-1162
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Incidence Coloring—Cold Cases
Autorzy:
Kardoš, František
Maceková, Mária
Mockovčiaková, Martina
Sopena, Éric
Soták, Roman
Powiązania:
https://bibliotekanauki.pl/articles/32083735.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
incidence coloring
incidence chromatic number
planar graph
maximum average degree
Opis:
An incidence in a graph G is a pair (v, e) where v is a vertex of G and e is an edge of G incident to v. Two incidences (v, e) and (u, f) are adjacent if at least one of the following holds: (i) v = u, (ii) e = f, or (iii) edge vu is from the set {e, f}. An incidence coloring of G is a coloring of its incidences assigning distinct colors to adjacent incidences. The minimum number of colors needed for incidence coloring of a graph is called the incidence chromatic number. It was proved that at most Δ(G) + 5 colors are enough for an incidence coloring of any planar graph G except for Δ(G) = 6, in which case at most 12 colors are needed. It is also known that every planar graph G with girth at least 6 and Δ(G) ≥ 5 has incidence chromatic number at most Δ(G) + 2. In this paper we present some results on graphs regarding their maximum degree and maximum average degree. We improve the bound for planar graphs with Δ(G) = 6. We show that the incidence chromatic number is at most Δ(G) + 2 for any graph G with mad(G) < 3 and Δ(G) = 4, and for any graph with mad(G)<103 and Δ(G) ≥ 8.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 345-354
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Properties of the Eigenvalues of the Net Laplacian Matrix of a Signed Graph
Autorzy:
Stanić, Zoran
Powiązania:
https://bibliotekanauki.pl/articles/32304147.pdf
Data publikacji:
2022-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
(net) Laplacian matrix
edge perturbations
largest eigenvalue
net-degree
Opis:
Given a signed graph $ \dot{G} $, let $ A_{ \dot{G} } $ and $ D_{\dot{G}}^\pm $ denote its standard adjacency matrix and the diagonal matrix of vertex net-degrees, respectively. The net Laplacian matrix of $ \dot{G} $ is defined to be $ N_{ \dot{G} } = D_{\dot{G}}^\pm - A_{ \dot{G} } $. In this study we give some properties of the eigenvalues of $ N_{ \dot{G} } $. In particular, we consider their behaviour under some edge perturbations, establish some relations between them and the eigenvalues of the standard Laplacian matrix and give some lower and upper bounds for the largest eigenvalue of $ N_{ \dot{G} } $.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 3; 893-903
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neighbor Product Distinguishing Total Colorings of Planar Graphs with Maximum Degree at least Ten
Autorzy:
Dong, Aijun
Li, Tong
Powiązania:
https://bibliotekanauki.pl/articles/32227944.pdf
Data publikacji:
2021-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
total coloring
neighbor product distinguishing coloring
planar graph
Opis:
A proper [k]-total coloring c of a graph G is a proper total coloring c of G using colors of the set [k] = {1, 2, . . ., k}. Let p(u) denote the product of the color on a vertex u and colors on all the edges incident with u. For each edge uv ∈ E(G), if p(u) ≠ p(v), then we say the coloring c distinguishes adjacent vertices by product and call it a neighbor product distinguishing k-total coloring of G. By X(G), we denote the smallest value of k in such a coloring of G. It has been conjectured by Li et al. that Δ(G) + 3 colors enable the existence of a neighbor product distinguishing total coloring. In this paper, by applying the Combinatorial Nullstellensatz, we obtain that the conjecture holds for planar graph with Δ(G) ≥ 10. Moreover, for planar graph G with Δ(G) ≥ 11, it is neighbor product distinguishing (Δ(G) + 2)-total colorable, and the upper bound Δ(G) + 2 is tight.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 4; 981-999
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decomposition of the Product of Cycles Based on Degree Partition
Autorzy:
Borse, Y. M.
Shaikh, S. R.
Powiązania:
https://bibliotekanauki.pl/articles/31343576.pdf
Data publikacji:
2019-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hypercube
Cartesian product
n-connected
regular
bipan- cyclic
spanning subgraph
Opis:
The Cartesian product of n cycles is a 2n-regular, 2n-connected and bi- pancyclic graph. Let G be the Cartesian product of n even cycles and let 2n = n1+ n2+ ・ ・ ・ + nk with k ≥ 2 and ni ≥ 2 for each i. We prove that if k = 2, then G can be decomposed into two spanning subgraphs G1 and G2 such that each Gi is ni-regular, ni-connected, and bipancyclic or nearly bipancyclic. For k > 2, we establish that if all ni in the partition of 2n are even, then G can be decomposed into k spanning subgraphs G1, G2, . . ., Gk such that each Gi is ni-regular and ni-connected. These results are analogous to the corresponding results for hypercubes.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 1; 241-256
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Equating κ Maximum Degrees in Graphs without Short Cycles
Autorzy:
Fürst, Maximilian
Gentner, Michael
Jäger, Simon
Rautenbach, Dieter
Henning, Michael A.
Powiązania:
https://bibliotekanauki.pl/articles/31523205.pdf
Data publikacji:
2020-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
maximum degree
repeated degrees
repetition number
Opis:
For an integer $k$ at least 2, and a graph $G$, let $f_k(G)$ be the minimum cardinality of a set $X$ of vertices of $G$ such that $G − X$ has either $k$ vertices of maximum degree or order less than $k$. Caro and Yuster [Discrete Mathematics 310 (2010) 742–747] conjectured that, for every $k$, there is a constant $c_k$ such that \(f_k(G)≤c_k\sqrt{n(G)}\) for every graph $G$. Verifying a conjecture of Caro, Lauri, and Zarb [arXiv:1704.08472v1], we show the best possible result that, if t is a positive integer, and $F$ is a forest of order at most \(1/6(t^3+6t^2+17t+12)\), then $f_2(F) ≤ t$. We study $f_3(F)$ for forests $F$ in more detail obtaining similar almost tight results, and we establish upper bounds on $f_k(G)$ for graphs $G$ of girth at least 5. For graphs $G$ of girth more than $2p$, for $p$ at least 3, our results imply \(f_k(G)=O\bigg(n(G)\frac{p+1}{3_p}\bigg)\). Finally, we show that, for every fixed $k$, and every given forest $F$, the value of $f_k(F)$ can be determined in polynomial time.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 3; 841-853
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Constructive Extension of the Characterization on Potentially Ks,t-Bigraphic Pairs
Autorzy:
Guo, Ji-Yun
Yin, Jian-Hua
Powiązania:
https://bibliotekanauki.pl/articles/31342128.pdf
Data publikacji:
2017-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
degree sequence
bigraphic pair
potentially K s,t -bigraphic pair
Opis:
Let Ks,t be the complete bipartite graph with partite sets of size s and t. Let L1 = ([a1, b1], . . ., [am, bm]) and L2 = ([c1, d1], . . ., [cn, dn]) be two sequences of intervals consisting of nonnegative integers with a1 ≥ a2 ≥ . . . ≥ am and c1 ≥ c2 ≥ . . . ≥ cn. We say that L = (L1; L2) is potentially Ks,t (resp. As,t)-bigraphic if there is a simple bipartite graph G with partite sets X = {x1, . . ., xm} and Y = {y1, . . ., yn} such that ai ≤ dG(xi) ≤ bi for 1 ≤ i ≤ m, ci ≤ dG(yi) ≤ di for 1 ≤ i ≤ n and G contains Ks,t as a subgraph (resp. the induced subgraph of {x1, . . ., xs, y1, . . ., yt} in G is a Ks,t). In this paper, we give a characterization of L that is potentially As,t-bigraphic. As a corollary, we also obtain a characterization of L that is potentially Ks,t-bigraphic if b1 ≥ b2 ≥ . . . ≥ bm and d1 ≥ d2 ≥ . . . ≥ dn. This is a constructive extension of the characterization on potentially Ks,t-bigraphic pairs due to Yin and Huang (Discrete Math. 312 (2012) 1241–1243).
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 1; 251-259
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral Radius and Hamiltonicity of Graphs
Autorzy:
Yu, Guidong
Fang, Yi
Fan, Yizheng
Cai, Gaixiang
Powiązania:
https://bibliotekanauki.pl/articles/31343181.pdf
Data publikacji:
2019-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spectral radius
singless Laplacian spectral radius
traceable
Hamiltonian-connected
traceable from every vertex
minimum degree
Opis:
In this paper, we study the Hamiltonicity of graphs with large minimum degree. Firstly, we present some conditions for a simple graph to be Hamilton-connected and traceable from every vertex in terms of the spectral radius of the graph or its complement, respectively. Secondly, we give the conditions for a nearly balanced bipartite graph to be traceable in terms of spectral radius, signless Laplacian spectral radius of the graph or its quasi-complement, respectively.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 4; 951-974
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Implicit Heavy Subgraphs and Hamiltonicity of 2-Connected Graphs
Autorzy:
Zheng, Wei
Wideł, Wojciech
Wang, Ligong
Powiązania:
https://bibliotekanauki.pl/articles/32083821.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
implicit degree
implicit o-heavy
implicit f-heavy
implicit c-heavy
Hamilton cycle
Opis:
A graph G of order n is implicit claw-heavy if in every induced copy of K1,3 in G there are two non-adjacent vertices with sum of their implicit degrees at least n. We study various implicit degree conditions (including, but not limiting to, Ore- and Fan-type conditions) imposing of which on specific induced subgraphs of a 2-connected implicit claw-heavy graph ensures its Hamiltonicity. In particular, we improve a recent result of [X. Huang, Implicit degree condition for Hamiltonicity of 2-heavy graphs, Discrete Appl. Math. 219 (2017) 126–131] and complete the characterizations of pairs of o-heavy and f-heavy subgraphs for Hamiltonicity of 2-connected graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 167-181
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral Conditions for Graphs to be k-Hamiltonian or k-Path-Coverable
Autorzy:
Liu, Weijun
Liu, Minmin
Zhang, Pengli
Feng, Lihua
Powiązania:
https://bibliotekanauki.pl/articles/32083834.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spectral radius
minimum degree
k -Hamiltonian
k -path-coverable
Opis:
A graph G is k-Hamiltonian if for all X ⊂ V (G) with |X| ≤ k, the subgraph induced by V (G) \ X is Hamiltonian. A graph G is k-path-coverable if V (G) can be covered by k or fewer vertex disjoint paths. In this paper, by making use of the vertex degree sequence and an appropriate closure concept (due to Bondy and Chvátal), we present sufficient spectral conditions of a connected graph with fixed minimum degree and large order to be k-Hamiltonian or k-path-coverable.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 161-179
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Existence of Regular Nut Graphs for Degree at Most 11
Autorzy:
Fowler, Patrick W.
Gauci, John Baptist
Goedgebeur, Jan
Pisanski, Tomaž
Sciriha, Irene
Powiązania:
https://bibliotekanauki.pl/articles/31550028.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
nut graph
core graph
regular graph
nullity
Opis:
A nut graph is a singular graph with one-dimensional kernel and corresponding eigenvector with no zero elements. The problem of determining the orders n for which d-regular nut graphs exist was recently posed by Gauci, Pisanski and Sciriha. These orders are known for d ≤ 4. Here we solve the problem for all remaining cases d ≤ 11 and determine the complete lists of all d-regular nut graphs of order n for small values of d and n. The existence or non-existence of small regular nut graphs is determined by a computer search. The main tool is a construction that produces, for any d-regular nut graph of order n, another d-regular nut graph of order n+2d. If we are given a sufficient number of d-regular nut graphs of consecutive orders, called seed graphs, this construction may be applied in such a way that the existence of all d-regular nut graphs of higher orders is established. For even d the orders n are indeed consecutive, while for odd d the orders n are consecutive even numbers. Furthermore, necessary conditions for combinations of order and degree for vertex-transitive nut graphs are derived.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 533-557
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distribution of Contractible Edges and the Structure of Noncontractible Edges having Endvertices with Large Degree in a 4-Connected Graph
Autorzy:
Nakamura, Shunsuke
Powiązania:
https://bibliotekanauki.pl/articles/32323873.pdf
Data publikacji:
2021-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
4-connected graph
contractible edge
cross free
Opis:
Let G be a 4-connected graph G, and let Ec(G) denote the set of 4-contractible edges of G. We prove results concerning the distribution of edges in Ec(G). Roughly speaking, we show that there exists a set K0 and a mapping φ : K0 → Ec(G) such that |φ-1(e)| ≤ 4 for each e ∈ Ec(G).
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 4; 1051-1066
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neighbor Sum Distinguishing Total Choosability of IC-Planar Graphs
Autorzy:
Song, Wen-Yao
Miao, Lian-Ying
Duan, Yuan-Yuan
Powiązania:
https://bibliotekanauki.pl/articles/32083736.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
neighbor sum distinguishing total choosability
maximum degree
IC-planar graph
Combinatorial Nullstellensatz
Opis:
Two distinct crossings are independent if the end-vertices of the crossed pair of edges are mutually different. If a graph $G$ has a drawing in the plane such that every two crossings are independent, then we call $G$ a plane graph with independent crossings or IC-planar graph for short. A proper total-$k$-coloring of a graph $G$ is a mapping $ c : V (G) \cup E(G) \rightarrow \{ 1, 2, . . ., k \} $ such that any two adjacent elements in $ V (G) \cup E(G) $ receive different colors. Let $ \Sigma_c (v) $ denote the sum of the color of a vertex $v$ and the colors of all incident edges of $v$. A total-$k$-neighbor sum distinguishing-coloring of $G$ is a total-$k$-coloring of $G$ such that for each edge $ uv \in E(G)$, $\Sigma_c (u) \ne \Sigma_c (v) $. The least number $k$ needed for such a coloring of $G$ is the neighbor sum distinguishing total chromatic number, denoted by $ \chi_\Sigma^{''} (G) $. In this paper, it is proved that if $G$ is an IC-planar graph with maximum degree $ \Delta (G) $, then $ ch_\Sigma^{''} (G) \le \text{max} \{ \Delta (G)+3, 17 \} $, where $ ch_\Sigma^{''} (G) $ is the neighbor sum distinguishing total choosability of $G$.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 331-344
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Neighborhood Condition for Fractional ID-[A, B]-Factor-Critical Graphs
Autorzy:
Zhou, Sizhong
Yang, Fan
Sun, Zhiren
Powiązania:
https://bibliotekanauki.pl/articles/31340936.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
minimum degree
neighborhood
fractional [a
b]-factor
fractional ID-[a
b]-factor-critical graph
Opis:
Let $G$ be a graph of order $n$, and let $a$ and $b$ be two integers with $ 1 \le a \le b $. Let $ h : E(G) \rightarrow [0, 1] $ be a function. If \( a \le \Sigma_{ e \ni x } h(e) \le b \) holds for any $ x \in V (G) $, then we call $ G[F_h] $ a fractional $ [a, b] $-factor of $ G $ with indicator function $ h $, where $ F_h = \{ e \in E(G) : h(e) > 0 \} $. A graph $G$ is fractional independent-set-deletable $[a, b]$-factor-critical (in short, fractional ID-$[a, b]$-factor-critical) if $ G − I $ has a fractional $ [a, b] $-factor for every independent set $I$ of $G$. In this paper, it is proved that if $ n \ge \frac{(a+2b)(2a+2b-3)+1}{b} $, $ \delta (G) \ge \frac{bn}{a+2b} + a $ and $ | N_G(x) \cup N_G(y) | \ge \frac{(a+b)n}{a+2b} $ for any two nonadjacent vertices $ x, y \in V (G) $, then $ G $ is fractional ID-$[a, b]$-factor-critical. Furthermore, it is shown that this result is best possible in some sense.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 409-418
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The List Edge Coloring and List Total Coloring of Planar Graphs with Maximum Degree at Least 7
Autorzy:
Sun, Lin
Wu, Jianliang
Wang, Bing
Liu, Bin
Powiązania:
https://bibliotekanauki.pl/articles/31348158.pdf
Data publikacji:
2020-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar graph
list edge coloring
list total coloring
Opis:
A graph $G$ is edge $k$-choosable (respectively, total $k$-choosable) if, whenever we are given a list $L(x)$ of colors with $|L(x)| = k$ for each $x ∈ E(G) (x ∈ E(G) ∪ V (G))$, we can choose a color from $L(x)$ for each element $x$ such that no two adjacent (or incident) elements receive the same color. The list edge chromatic index $χ_l^′(G)$ (respectively, the list total chromatic number $χ_l^{′′}(G))$ of $G$ is the smallest integer $k$ such that $G$ is edge (respectively, total) $k$-choosable. In this paper, we focus on a planar graph $G$, with maximum degree $Δ (G) ≥ 7$ and with some structural restrictions, satisfies $χ_l^′(G) = Δ (G)$ and $χ_l^{′′}(G) = Δ (G) + 1$.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 4; 1005-1024
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Describing Neighborhoods of 5-Vertices in 3-Polytopes with Minimum Degree 5 and Without Vertices of Degrees from 7 to 11
Autorzy:
Borodin, Oleg V.
Ivanova, Anna O.
Kazak, Olesya N.
Powiązania:
https://bibliotekanauki.pl/articles/31342287.pdf
Data publikacji:
2018-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar graph
structure properties
3-polytope
neighborhood
Opis:
In 1940, Lebesgue proved that every 3-polytope contains a 5-vertex for which the set of degrees of its neighbors is majorized by one of the following sequences: (6, 6, 7, 7, 7), (6, 6, 6, 7, 9), (6, 6, 6, 6, 11), (5, 6, 7, 7, 8), (5, 6, 6, 7, 12), (5, 6, 6, 8, 10), (5, 6, 6, 6, 17), (5, 5, 7, 7, 13), (5, 5, 7, 8, 10), (5, 5, 6, 7, 27), (5, 5, 6, 6, ∞), (5, 5, 6, 8, 15), (5, 5, 6, 9, 11), (5, 5, 5, 7, 41), (5, 5, 5, 8, 23), (5, 5, 5, 9, 17), (5, 5, 5, 10, 14), (5, 5, 5, 11, 13). In this paper we prove that every 3-polytope without vertices of degree from 7 to 11 contains a 5-vertex for which the set of degrees of its neighbors is majorized by one of the following sequences: (5, 5, 6, 6, ∞), (5, 6, 6, 6, 15), (6, 6, 6, 6, 6), where all parameters are tight.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 3; 615-625
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light Minor 5-Stars in 3-Polytopes with Minimum Degree 5 and No 6-Vertices
Autorzy:
Borodin, Oleg V.
Ivanova, Anna O.
Vasil’eva, Ekaterina I.
Powiązania:
https://bibliotekanauki.pl/articles/31348169.pdf
Data publikacji:
2020-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar map
planar graph
3-polytope
structural properties
5-star
weight
height
Opis:
In 1940, Lebesgue gave an approximate description of the neighborhoods of 5-vertices in the class P5 of 3-polytopes with minimum degree 5. Given a 3-polytope P, by w(P) denote the minimum of the degree-sum (weight) of the neighborhoods of 5-vertices (minor 5-stars) in P. In 1996, Jendrol’ and Madaras showed that if a polytope P in P5 is allowed to have a 5-vertex adjacent to four 5-vertices, then w(P) can be arbitrarily large. For each P in P5 without vertices of degree 6 and 5-vertices adjacent to four 5-vertices, it follows from Lebesgue’s Theorem that w(P) ≤ 68. Recently, this bound was lowered to w(P) ≤ 55 by Borodin, Ivanova, and Jensen and then to w(P) ≤ 51 by Borodin and Ivanova. In this note, we prove that every such polytope P satisfies w(P) ≤ 44, which bound is sharp.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 4; 985-994
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Universality in Graph Properties with Degree Restrictions
Autorzy:
Broere, Izak
Heidema, Johannes
Mihók, Peter
Powiązania:
https://bibliotekanauki.pl/articles/30146518.pdf
Data publikacji:
2013-07-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
countable graph
universal graph
induced-hereditary
k-degenerate graph
graph with colouring number at most k + 1
graph property with assignment
Opis:
Rado constructed a (simple) denumerable graph R with the positive integers as vertex set with the following edges: For given m and n with m < n, m is adjacent to n if n has a 1 in the m’th position of its binary expansion. It is well known that R is a universal graph in the set ℐc of all countable graphs (since every graph in ℐc is isomorphic to an induced subgraph of R). A brief overview of known universality results for some induced-hereditary subsets of ℐc is provided. We then construct a k-degenerate graph which is universal for the induced-hereditary property of finite k-degenerate graphs. In order to attempt the corresponding problem for the property of countable graphs with colouring number at most k + 1, the notion of a property with assignment is introduced and studied. Using this notion, we are able to construct a universal graph in this graph property and investigate its attributes.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 3; 477-492
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Po co psychologia?
What is psychology for?
Autorzy:
Brzeziński, Jerzy Marian
Powiązania:
https://bibliotekanauki.pl/articles/1178119.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Kazimierza Wielkiego w Bydgoszczy
Tematy:
5-year master’s degree
Empirically Based Assessment
antireductionism
empirical research
empirical theory
ethical awareness
falsification
full-time
methodological awareness
plagiarism
program in psychology
psychology
science
scientific misconduct: fabrication
social practice
Opis:
Three main problems are considered. The first is that psychology should avoid any inclination towards neuroscience or a type of brain science. Making use of the achievements of natural sciences, psychology should take into regard the cultural conditions [determinants] and methods worked out in social sciences. Thus, it should adopt the antireductionistic methodological programme. The second problem is that psychology must reject the papers that entice with apparent scientific approach being actually of no real worth. Also the threat posed to psychological practice by pseudo-scientific monographs and pseudo-test should be recognised. They offer scientifically false basis of practical work of psychologists in the sphere of social practice. The third problem is that each psychological practice should be preceded by a psychological theory that is empirical and needs to be verified by a methodologically correct method. Thee underlying empirical psychological theory makes a given psychological practice sensible and ethical. The status of psychology as a science and the status of psychological practice are related to the quality of education of future psychologists. The author definitely opts for the model of full-time 5-year master’s degree studies (so against the Bologna model of 3-year licentiate (BA) followed by a 2-year master’s degree study (MA)), supplemented with a one-year training under supervision of an experienced specialist. The effective and ethical work of professional psychologists in Poland suffers from the lack of legal regulations that would protect this profession against the infiltration of all kinds of charlatans offering pseudo-scientific diagnostic tools like e.g. the Tree test of Charles Koch and therapies like e.g. the Systemic Constellation of Bert Hellinger. Of utmost importance is development of not only methodological awareness but also ethical awareness in psychologists and students of psychology. Moreover, the education should bring the realisation of the effects and danger of scientific misconduct of FFP type, that is fabrication, falsification, plagiarism.
Źródło:
Polskie Forum Psychologiczne; 2014, XIX, 3; 285-304
1642-1043
Pojawia się w:
Polskie Forum Psychologiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Slater and Sub-k-Domination Number of a Graph with Applications to Domination and k-Domination
Autorzy:
Amos, David
Asplund, John
Brimkov, Boris
Davila, Randy
Powiązania:
https://bibliotekanauki.pl/articles/32083827.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Slater number
domination number
sub- k -domination number
k -domination number
degree sequence index strategy
Opis:
In this paper we introduce and study a new graph invariant derived from the degree sequence of a graph G, called the sub-k-domination number and denoted subk(G). This invariant serves as a generalization of the Slater number; in particular, we show that subk(G) is a computationally efficient sharp lower bound on the k-domination number of G, and improves on several known lower bounds. We also characterize the sub-k-domination numbers of several families of graphs, provide structural results on sub-k-domination, and explore properties of graphs which are subk(G)-critical with respect to addition and deletion of vertices and edges.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 209-225
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Theses without Iterated Modalities of Modal Logics Between C1 and S5. Part 2
Autorzy:
Pietruszczak, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/750008.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
first-degree theses of modal logics
theses without iterated modalities
Pollack’s theory of Basic Modal Logic
basic theories for modal logics between C1 and S5
Opis:
This is the second, out of two papers, in which we identify all logics between C1 and S5 having the same theses without iterated modalities. All these logics can be divided into certain groups. Each such group depends only on which of the following formulas are theses of all logics from this group: (N), (T), (D), ⌜(T)∨☐q⌝, and for any n > 0 a formula ⌜(T) ∨ (altn)⌝, where (T) has not the atom ‘q’, and (T) and (altn) have no common atom. We generalize Pollack’s result from [1], where he proved that all modal logics between S1 and S5 have the same theses which does not involve iterated modalities (i.e., the same first-degree theses).
Źródło:
Bulletin of the Section of Logic; 2017, 46, 3/4
0138-0680
2449-836X
Pojawia się w:
Bulletin of the Section of Logic
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Theses Without Iterated Modalities of Modal Logics Between C1 and S5. Part 1
Autorzy:
Pietruszczak, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/749944.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
first-degree theses of modal logics
theses without iterated modalities
Pollack’s theory of Basic Modal Logic
basic theories for modal logics between C1 and S5
Opis:
This is the first, out of two papers, in which we identify all logics between C1 and S5 having the same theses without iterated modalities. All these logics canbe divided into certain groups. Each such group depends only on which of thefollowing formulas are theses of all logics from this group: (N), (T), (D), ⌜(T)∨ ☐q⌝,and for any n > 0 a formula ⌜(T) ∨ (altn)⌝, where (T) has not the atom ‘q’, and(T) and (altn) have no common atom. We generalize Pollack’s result from [12],where he proved that all modal logics between S1 and S5 have the same theseswhich does not involve iterated modalities (i.e., the same first-degree theses).
Źródło:
Bulletin of the Section of Logic; 2017, 46, 1/2
0138-0680
2449-836X
Pojawia się w:
Bulletin of the Section of Logic
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Niepewność typu A pomiaru o obserwacjach samoskorelowanych
Uncertainty of type A of the measurement with auto-correlated observations
Autorzy:
Warsza, Z. L.
Zięba, A.
Powiązania:
https://bibliotekanauki.pl/articles/157535.pdf
Data publikacji:
2012
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
teoria pomiaru
menzurand
niepewność
autokorelacja
efektywna liczba obserwacji
efektywna liczba stopni swobody
measurement theory
measurand
uncertainty
autocorrelation
effective number of observations
effective degree of freedom
Opis:
Omówiono ograniczenia zalecanej w Przewodniku GUM metody wyznaczania niepewności pomiarów typu A. Opisano rozszerzenie jej na pomiary o równomiernym próbkowaniu menzurandu z uwzględnieniem wpływu funkcji autokorelacji wartości obserwacji. Przedstawiono poprzedzającą niezbędną identyfikację i usunięcie składowych regularnie zmiennych z surowych danych pomiarowych. Podano wzory dla równoważnej, tzw. efektywnej liczby nieskorelowanych obserwacji ηeff, zależnej od funkcji autokorelacji ρk próbki. Umożliwia ona poprawne wyznaczenie niepewności pomiarów według dotychczasowej procedury GUM. Omówiono sposób oszacowania estymaty funkcji autokorelacji τk z danych pomiarowych. Rozważania zilustrowano przykładami liczbowymi.
Expanding of the application range of the present formalism of GUM to the case of regularly sampled mutually correlated observations is proposed. First, the obvious previous identification and cleaning of the raw sample data from regularly variable components is discussed briefly. The formulae for standard deviation and standard deviation of the mean are expressed with the use of the so-called effective number of observation ηeff. This quantity depends of real number of observation n and elements of the autocorrelation function ρk. The another parameter named effective degree of freedom νeff describes the dispersion of both estimators of standard deviation and can be used to calculate the expanded uncertainty. We also show how to adopt this formalism if only an estimate τk of the ACF derived from a sample is available. A novel method is introduced based on truncation of the τk function at the point of its first transit through zero (FTZ). This method can be applied to non-negative ACFs which occurs most often in practice. Considerations are illustrated by the numerical example.
Źródło:
Pomiary Automatyka Kontrola; 2012, R. 58, nr 2, 2; 157-162
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Miasto jako “obietnica zawsze nowych odkryć” w kontekście archeologii potrzeganej jako dyscyplina skazana na resocjalizację i z perspektywy archeologii drugiego stopnia
THE CITY AS A “PROMISE OF EVE NEW DISCOVERIES” IN THE CONTEXT OF RE-SOCIALIZED ARCHAEOLOGY AND THROUGHT THE PRISM OF SECOND DEGRE ARCHAEOLOGY
Autorzy:
Zalewska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/497963.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Rzeszowski. Instytut Archeologii Uniwersytetu Rzeszowskiego. Muzeum Okręgowe w Rzeszowie
Tematy:
URBAN ARCHAEOLOGY
THEORY OF ARCHAEOLOGY
DEFINITION OF THE TERM CITY
SIMULTANEITY OF THE NON-SIMULTANEOUS
RE-SOCIALIZED ARCHAEOLOGY
SECOND DEGREE ARCHAEOLOGY
ETHNIC OF SOCIAL CONSEQUENCES
THE SAINT DENIS CASE
Opis:
This article sketches the complex phenomenon of the city and the diverse understanding of archaeological practice within the city, both in cognitive and social terms. Three ways of approaching the city are examined – as material and semiotic cognitive phenomenon (perceived as historical and archaeological source of knowledge about the past), as the composition of past and present social interactions (that could allow archaeology to construct an inter-subjective understanding of the importance of material meaning), and as a subject conducive to establishing ethical foundations for contemporaneous social practice that produces discourses about past social processes and present social values. Ways to connect these three domains are explored – through a reconsideration of archaeological entities and archaeological practice via theoretical propositions of: re-socialized archaeology, second degree archaeology and ethics of social consequences. The author argues that urban archaeology has great potential to become the context for rethinking the nature of archaeological enquiry and the kind of history, narratives and representations based on it.
Źródło:
Analecta Archaeologica Ressoviensia; 2012, 7; 25-66
2084-4409
Pojawia się w:
Analecta Archaeologica Ressoviensia
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-68 z 68

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