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Wyświetlanie 1-14 z 14
Tytuł:
Toughness, Forbidden Subgraphs, and Hamilton-Connected Graphs
Autorzy:
Zheng, Wei
Broersma, Hajo
Wang, Ligong
Powiązania:
https://bibliotekanauki.pl/articles/32361744.pdf
Data publikacji:
2022-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
toughness
forbidden subgraph
Hamilton-connected graph
Hamiltonicity
Opis:
A graph G is called Hamilton-connected if for every pair of distinct vertices {u, v} of G there exists a Hamilton path in G that connects u and v. A graph G is said to be t-tough if t·ω(G − X) ≤ |X| for all X ⊆ V (G) with ω(G − X) > 1. The toughness of G, denoted τ (G), is the maximum value of t such that G is t-tough (taking τ (Kn) = ∞ for all n ≥ 1). It is known that a Hamilton-connected graph G has toughness τ (G) > 1, but that the reverse statement does not hold in general. In this paper, we investigate all possible forbidden subgraphs H such that every H-free graph G with τ (G) > 1 is Hamilton-connected. We find that the results are completely analogous to the Hamiltonian case: every graph H such that any 1-tough H-free graph is Hamiltonian also ensures that every H-free graph with toughness larger than one is Hamilton-connected. And similarly, there is no other forbidden subgraph having this property, except possibly for the graph K1 ∪ P4 itself. We leave this as an open case.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 1; 187-196
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rozpoznawanie wzorców cyfrowych pisma ręcznego z użyciem robota edukacyjnego
Handwritten digit pattern recognition based on education robot
Autorzy:
Dimitrova-Grekow, T.
Sworowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/155788.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
rozpoznawanie wzorców
pismo ręczne
drzewo decyzyjne
graf Hamiltona
pattern recognition
handwritten numbers
decision tree
Hamilton graph
Opis:
Niniejsza praca prezentuje zaimplementowanie systemu rozpoznającego ręcznie pisane wzorce cyfrowe z użyciem mobilnego układu edukacyjnego LEGO Mindstorms NXT. Został on wybrany ze względu na prostotę w konstrukcji i równocześnie możliwość złożonego programowania. Zbudowany w ramach projektu robot skanujący znaki pisma ręcznego spełnił założenia początkowe. Wyniki zaimplementowanego algorytmu rozpoznającego również pokryły się z oczekiwaniami - system osiągnął skuteczność na poziomie 100% w warunkach idealnych. We względnie utrudnionych warunkach skuteczność spadła do 91%.
Pattern recognition can be classified depending on the data source, the way data is read, processed and on the implementation of the recognition itself [9]. This paper presents a method of pattern recognition identifying handwritten Arabic numbers. The data is collected by a Lego Mindstorms NXT 2.0 mobile robot using a color sensor. Usually, the input data are gathered by high-precision equipment [2,5], and or have an additional multi-sensor subsystem [1]. Very successive recognition approaches are based on neural networks [3, 4,6] additional supported by statistic [8]. Unfortunately, all these methods require powerful calculations. The environment data read by such a simple educational robot contains many drawbacks: noises, relative stabile confidence etc. The solution we propose solves to some extent the problem using a minimal hardware equipment (Fig. 4) and undemanding computation effort. The built recognition system is divided into two parts. The first part presents the data set collection - the hand-written digits scanning (Fig.1) and the data initial processing. The second one consists of primary and secondary classification (Figs. 2 and 3). The algorithm is based on the undirected graph model [10]. The results of the conducted experiments are very interesting (Tabs. 1 and 2). This encourages further exploration of implementation of the well-known and new recognition methods on minimal hardware.
Źródło:
Pomiary Automatyka Kontrola; 2013, R. 59, nr 8, 8; 812-814
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research problems from the 18th Workshop '3in1' 2009
Autorzy:
Meszka, M. [ed.]
Powiązania:
https://bibliotekanauki.pl/articles/255619.pdf
Data publikacji:
2010
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Hamilton-connected graph
hamiltonian graph
dominating cycle
bihomogeneously traceble graph
Opis:
A collection of open problems that were posed at the 18th Workshop '3in1', held on November 26-28, 2009 in Krakow, Poland. The problems are presented by Zdenek Ryjacek in "Does the Thomassen's conjecture imply N=NP?" and "Dominating cycles and hamiltonian prisms", and by Carol T. Zamfirescu in "Two problems on bihomogeneously traceable digraphs".
Źródło:
Opuscula Mathematica; 2010, 30, 4; 527-532
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Perfect Set of Euler Tours of Kp,p,p
Autorzy:
Govindan, T.
Muthusamy, A.
Powiązania:
https://bibliotekanauki.pl/articles/31340779.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
compatible Euler tour
line graph
Hamilton cycle decomposition
Opis:
Bermond conjectured that if G is Hamilton cycle decomposable, then L(G), the line graph of G, is Hamilton cycle decomposable. In this paper, we construct a perfect set of Euler tours for the complete tripartite graph Kp,p,p for any prime p and hence prove Bermond’s conjecture for G = Kp,p,p.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 783-796
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pancyclicity when each Cycle Must Pass Exactly k Hamilton Cycle Chords
Autorzy:
Affif Chaouche, Fatima
Rutherford, Carrie G.
Whitty, Robin W.
Powiązania:
https://bibliotekanauki.pl/articles/31339337.pdf
Data publikacji:
2015-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
extremal graph theory
pancyclic graph
Hamilton cycle
Opis:
It is known that Θ(log n) chords must be added to an n-cycle to produce a pancyclic graph; for vertex pancyclicity, where every vertex belongs to a cycle of every length, Θ(n) chords are required. A possibly ‘intermediate’ variation is the following: given k, 1 ≤ k ≤ n, how many chords must be added to ensure that there exist cycles of every possible length each of which passes exactly k chords? For fixed k, we establish a lower bound of Ω(n1/k) on the growth rate.
Źródło:
Discussiones Mathematicae Graph Theory; 2015, 35, 3; 533-539
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On constant-weight TSP-tours
Autorzy:
Jones, Scott
Kayll, P.
Mohar, Bojan
Wallis, Walter
Powiązania:
https://bibliotekanauki.pl/articles/743167.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph labelling
complete graph
travelling salesman problem
Hamilton cycle
one-factor
two-factor
k-factor
constant-weight
local matching conditions
edge label growth-rate
Sidon sequence
well-spread sequence
Opis:
Is it possible to label the edges of Kₙ with distinct integer weights so that every Hamilton cycle has the same total weight? We give a local condition characterizing the labellings that witness this question's perhaps surprising affirmative answer. More generally, we address the question that arises when "Hamilton cycle" is replaced by "k-factor" for nonnegative integers k. Such edge-labellings are in correspondence with certain vertex-labellings, and the link allows us to determine (up to a constant factor) the growth rate of the maximum edge-label in a "most efficient" injective metric trivial-TSP labelling.
Źródło:
Discussiones Mathematicae Graph Theory; 2003, 23, 2; 287-307
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Linear forests and ordered cycles
Autorzy:
Chen, Guantao
Faudree, Ralph
Gould, Ronald
Jacobson, Michael
Lesniak, Linda
Pfender, Florian
Powiązania:
https://bibliotekanauki.pl/articles/744529.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
hamilton cycles
graph linkages
Opis:
A collection $L = P¹ ∪ P² ∪ ... ∪ P^t$ (1 ≤ t ≤ k) of t disjoint paths, s of them being singletons with |V(L)| = k is called a (k,t,s)-linear forest. A graph G is (k,t,s)-ordered if for every (k,t,s)-linear forest L in G there exists a cycle C in G that contains the paths of L in the designated order as subpaths. If the cycle is also a hamiltonian cycle, then G is said to be (k,t,s)-ordered hamiltonian. We give sharp sum of degree conditions for nonadjacent vertices that imply a graph is (k,t,s)-ordered hamiltonian.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 3; 359-372
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heavy cycles in weighted graphs
Autorzy:
Bondy, J.
Broersma, Hajo
van den Heuvel, Jan
Veldman, Henk
Powiązania:
https://bibliotekanauki.pl/articles/743527.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
weighted graph
(long, optimal, Hamilton) cycle
(edge-, vertex-)weighting
weighted degree
Opis:
An (edge-)weighted graph is a graph in which each edge e is assigned a nonnegative real number w(e), called the weight of e. The weight of a cycle is the sum of the weights of its edges, and an optimal cycle is one of maximum weight. The weighted degree w(v) of a vertex v is the sum of the weights of the edges incident with v. The following weighted analogue (and generalization) of a well-known result by Dirac for unweighted graphs is due to Bondy and Fan. Let G be a 2-connected weighted graph such that w(v) ≥ r for every vertex v of G. Then either G contains a cycle of weight at least 2r or every optimal cycle of G is a Hamilton cycle. We prove the following weighted analogue of a generalization of Dirac's result that was first proved by Pósa. Let G be a 2-connected weighted graph such that w(u)+w(v) ≥ s for every pair of nonadjacent vertices u and v. Then G contains either a cycle of weight at least s or a Hamilton cycle. Examples show that the second conclusion cannot be replaced by the stronger second conclusion from the result of Bondy and Fan. However, we characterize a natural class of edge-weightings for which these two conclusions are equivalent, and show that such edge-weightings can be recognized in time linear in the number of edges.
Źródło:
Discussiones Mathematicae Graph Theory; 2002, 22, 1; 7-15
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hamilton decompositions of line graphs of some bipartite graphs
Autorzy:
Pike, David
Powiązania:
https://bibliotekanauki.pl/articles/744372.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Hamilton cycles
graph decompositions
line graphs
Opis:
Some bipartite Hamilton decomposable graphs that are regular of degree δ ≡ 2 (mod 4) are shown to have Hamilton decomposable line graphs. One consequence is that every bipartite Hamilton decomposable graph G with connectivity κ(G) = 2 has a Hamilton decomposable line graph L(G).
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 3; 303-310
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hamilton cycles in split graphs with large minimum degree
Autorzy:
Tan, Ngo
Hung, Le
Powiązania:
https://bibliotekanauki.pl/articles/744406.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Hamilton cycle
split graph
bipartite graph
Opis:
A graph G is called a split graph if the vertex-set V of G can be partitioned into two subsets V₁ and V₂ such that the subgraphs of G induced by V₁ and V₂ are empty and complete, respectively. In this paper, we characterize hamiltonian graphs in the class of split graphs with minimum degree δ at least |V₁| - 2.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 1; 23-40
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hamilton Cycles in Double Generalized Petersen Graphs
Autorzy:
Sakamoto, Yutaro
Powiązania:
https://bibliotekanauki.pl/articles/31343695.pdf
Data publikacji:
2019-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
double generalized Petersen graph
Hamilton cycle
Opis:
Coxeter referred to generalizing the Petersen graph. Zhou and Feng modified the graphs and introduced the double generalized Petersen graphs (DGPGs). Kutnar and Petecki proved that DGPGs are Hamiltonian in special cases and conjectured that all DGPGs are Hamiltonian. In this paper, we prove the conjecture by constructing Hamilton cycles in any given DGPG.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 1; 117-123
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Edge condition for hamiltonicity in balanced tripartite graphs
Autorzy:
Adamus, J.
Powiązania:
https://bibliotekanauki.pl/articles/255875.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Hamilton cycle
pancyclicity
tripartite graph
edge condition
Opis:
A well-known theorem of Entringer and Schmeichel asserts that a balanced bipartite graph of order 2n obtained from the complete balanced bipartite Kn,n by removing at most n - 2 edges, is bipancyclic. We prove an analogous result for balanced tripartite graphs: If G is a balanced tripartite graph of order 3n and size at least 3n(2) - 2n + 2, then G contains cycles of all lengths.
Źródło:
Opuscula Mathematica; 2009, 29, 4; 337-343
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A σ₃ type condition for heavy cycles in weighted graphs
Autorzy:
Zhang, Shenggui
Li, Xueliang
Broersma, Hajo
Powiązania:
https://bibliotekanauki.pl/articles/743462.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
weighted graph
(long, heavy, Hamilton) cycle
weighted degree
(weighted) degree sum
Opis:
A weighted graph is a graph in which each edge e is assigned a non-negative number w(e), called the weight of e. The weight of a cycle is the sum of the weights of its edges. The weighted degree $d^w(v)$ of a vertex v is the sum of the weights of the edges incident with v. In this paper, we prove the following result: Suppose G is a 2-connected weighted graph which satisfies the following conditions: 1. The weighted degree sum of any three independent vertices is at least m; 2. w(xz) = w(yz) for every vertex z ∈ N(x)∩N(y) with d(x,y) = 2; 3. 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 Hamilton cycle or a cycle of weight at least 2m/3. This generalizes a theorem of Fournier and Fraisse on the existence of long cycles in k-connected unweighted graphs in the case k = 2. Our proof of the above result also suggests a new proof to the theorem of Fournier and Fraisse in the case k = 2.
Źródło:
Discussiones Mathematicae Graph Theory; 2001, 21, 2; 159-166
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Note on Barnette’s Conjecture
Autorzy:
Harant, Jochen
Powiązania:
https://bibliotekanauki.pl/articles/30146724.pdf
Data publikacji:
2013-03-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
planar graph
Hamilton cycle
Barnette’s Conjecture
Opis:
Barnette conjectured that each planar, bipartite, cubic, and 3-connected graph is hamiltonian. We prove that this conjecture is equivalent to the statement that there is a constant c > 0 such that each graph G of this class contains a path on at least c|V (G)| vertices.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 1; 133-137
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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