Three Types of Two-Disjoint-Cycle-Cover Pancyclicity and Their Applications to Cycle Embedding in Locally Twisted Cubes

2019 ◽  
Author(s):  
Tzu-Liang Kung ◽  
Hon-Chan Chen ◽  
Chia-Hui Lin ◽  
Lih-Hsing Hsu
Keyword(s):  
Disjoint Cycle ◽  
Cycle Cover ◽  
Disjoint Cycles ◽  
Locally Twisted Cubes ◽  
Twisted Cube ◽  
Vertex Disjoint ◽  
Twisted Cubes

Abstract A graph $G=(V,E)$ is two-disjoint-cycle-cover $[r_1,r_2]$-pancyclic if for any integer $l$ satisfying $r_1 \leq l \leq r_2$, there exist two vertex-disjoint cycles $C_1$ and $C_2$ in $G$ such that the lengths of $C_1$ and $C_2$ are $l$ and $|V(G)| - l$, respectively, where $|V(G)|$ denotes the total number of vertices in $G$. On the basis of this definition, we further propose Ore-type conditions for graphs to be two-disjoint-cycle-cover vertex/edge $[r_1,r_2]$-pancyclic. In addition, we study cycle embedding in the $n$-dimensional locally twisted cube $LTQ_n$ under the consideration of two-disjoint-cycle-cover vertex/edge pancyclicity.

Hamiltonian Cycles Passing Through Prescribed Edges in Locally Twisted Cubes

2021 ◽  
Author(s):  
Dongqin Cheng
Keyword(s):  
Hamiltonian Cycle ◽  
Disjoint Paths ◽  
Hamiltonian Cycles ◽  
Induced Subgraph ◽  
Locally Twisted Cubes ◽  
Twisted Cube ◽  
Vertex Disjoint ◽  
Cube Formula ◽  
Twisted Cubes

Let [Formula: see text] be a set of edges whose induced subgraph consists of vertex-disjoint paths in an [Formula: see text]-dimensional locally twisted cube [Formula: see text]. In this paper, we prove that if [Formula: see text] contains at most [Formula: see text] edges, then [Formula: see text] contains a Hamiltonian cycle passing through every edge of [Formula: see text], where [Formula: see text]. [Formula: see text] has a Hamiltonian cycle passing through at most one prescribed edge.

scholarly journals A fast $$(2 + \frac{2}{7})$$-approximation algorithm for capacitated cycle covering

2021 ◽  
Author(s):  
Vera Traub ◽  
Thorben Tröbst
Keyword(s):  
Vehicle Routing Problem ◽  
Covering Problem ◽  
Post Processing ◽  
Routing Problem ◽  
Cycle Cover ◽  
Disjoint Cycles ◽  
Processing Step ◽  
Number Of Cycles ◽  
Vertex Disjoint ◽  
Capacitated Vehicle

AbstractWe consider the capacitated cycle covering problem: given an undirected, complete graph G with metric edge lengths and demands on the vertices, we want to cover the vertices with vertex-disjoint cycles, each serving a demand of at most one. The objective is to minimize a linear combination of the total length and the number of cycles. This problem is closely related to the capacitated vehicle routing problem (CVRP) and other cycle cover problems such as min-max cycle cover and bounded cycle cover. We show that a greedy algorithm followed by a post-processing step yields a $$(2 + \frac{2}{7})$$ ( 2 + 2 7 ) -approximation for this problem by comparing the solution to a polymatroid relaxation. We also show that the analysis of our algorithm is tight and provide a $$2 + \epsilon $$ 2 + ϵ lower bound for the relaxation.

The Tightly Super 2-extra Connectivity and 2-extra Diagnosability of Locally Twisted Cubes

2017 ◽  
Vol 17 (02) ◽  
pp. 1750006 ◽  
Author(s):  
YUNXIA REN ◽  
SHIYING WANG
Keyword(s):  
Fault Tolerance ◽  
Fault Diagnosis ◽  
Interconnection Network ◽  
Connected Subgraph ◽  
Minimum Cardinality ◽  
Pmc Model ◽  
Locally Twisted Cubes ◽  
Twisted Cube ◽  
Twisted Cubes

Connectivity plays an important role in measuring the fault tolerance of an interconnection network [Formula: see text]. A faulty set [Formula: see text] is called a g-extra faulty set if every component of G − F has more than g nodes. A g-extra cut of G is a g-extra faulty set F such that G − F is disconnected. The minimum cardinality of g-extra cuts is said to be the g-extra connectivity of G. G is super g-extra connected if every minimum g-extra cut F of G isolates one connected subgraph of order g + 1. If, in addition, G − F has two components, one of which is the connected subgraph of order g + 1, then G is tightly [Formula: see text] super g-extra connected. Diagnosability is an important metric for measuring the reliability of G. A new measure for fault diagnosis of G restrains that every fault-free component has at least (g + 1) fault-free nodes, which is called the g-extra diagnosability of G. The locally twisted cube LTQn is applied widely. In this paper, it is proved that LTQn is tightly (3n − 5) super 2-extra connected for [Formula: see text], and the 2-extra diagnosability of LTQn is 3n − 3 under the PMC model ([Formula: see text]) and MM* model ([Formula: see text]).

Embedding of Binomial Trees in Locally Twisted Cubes with Link Faults

2014 ◽  
Vol 1049-1050 ◽  
pp. 1736-1740
Author(s):  
Lan Tao You
Keyword(s):  
Parallel Computing ◽  
Interconnection Network ◽  
Binomial Tree ◽  
Binomial Trees ◽  
Locally Twisted Cubes ◽  
Twisted Cube ◽  
Twisted Cubes

As a newly introduced interconnection network for parallel computing, the locally twisted cube possesses many desirable properties. In this paper, binomial tree embeddings in locally twisted cubes are studied. We present two major results in this paper: (1) For any integern≥ 2, ann-dimensional binomial treeBncan be embedded inLTQnwith dilation 1 by randomly choosing any vertex inLTQnas the root. (2) For any integern≥ 2, ann-dimensional binomial treeBncan be embedded inLTQnwith up ton− 1 faulty links inlog(n− 1) steps where dilation = 1. The results are optimal in the sense that the dilations of all embeddings are 1.

scholarly journals Embedding Complete Binary Trees into Locally Twisted Cubes

2012 ◽  
Vol 6-7 ◽  
pp. 70-75 ◽  
Author(s):  
Yue Juan Han ◽  
Jian Xi Fan ◽  
Lan Tao You ◽  
Yan Wang
Keyword(s):  
Parallel Computing ◽  
Binary Tree ◽  
Interconnection Network ◽  
Binary Trees ◽  
Complete Binary Tree ◽  
Locally Twisted Cubes ◽  
Twisted Cube ◽  
Twisted Cubes

The locally twisted cube is a newly introduced interconnection network for parallel computing, which possesses many desirable properties. In this paper, the problem of embedding complete binary trees into locally twisted cubes is studied.Let LTQn(V;E) denote the n-dimensional locally twisted cube.We find the following result in this paper: for any integern ≥ 2,we show that a complete binary tree with 2n—1 nodes can be embedded into the LTQn with dilation 2.

scholarly journals Graphs with many vertex-disjoint cycles

2012 ◽  
Vol Vol. 14 no. 2 (Graph Theory) ◽  
Author(s):  
Dieter Rautenbach ◽  
Friedrich Regen
Keyword(s):  
Graph Theory ◽  
Upper Bound ◽  
Linear Time ◽  
Simple Extension ◽  
Disjoint Cycles ◽  
Cyclomatic Number ◽  
Finite Set ◽  
Extension Rule ◽  
International Audience ◽  
Vertex Disjoint

Graph Theory International audience We study graphs G in which the maximum number of vertex-disjoint cycles nu(G) is close to the cyclomatic number mu(G), which is a natural upper bound for nu(G). Our main result is the existence of a finite set P(k) of graphs for all k is an element of N-0 such that every 2-connected graph G with mu(G)-nu(G) = k arises by applying a simple extension rule to a graph in P(k). As an algorithmic consequence we describe algorithms calculating minmu(G)-nu(G), k + 1 in linear time for fixed k.

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