共查询到20条相似文献,搜索用时 46 毫秒
1.
Let G = (V, E) be an undirected graph and C(G){{\mathcal C}(G)} denote the set of all cycles in G. We introduce a graph invariant cycle discrepancy, which we define as
${\rm cycdisc}(G) = \min_{\chi: V \mapsto \{+1, -1\}}
\max_{ C \in {\mathcal C} (G)}
\left|\sum_{v \in C}
\chi(v)\right|.${\rm cycdisc}(G) = \min_{\chi: V \mapsto \{+1, -1\}}
\max_{ C \in {\mathcal C} (G)}
\left|\sum_{v \in C}
\chi(v)\right|. 相似文献
2.
Let G be an edge-colored graph. A heterochromatic cycle of G is a cycle in which any pair of edges have distinct colors. Let d c (v), named the color degree of a vertex v, be defined as the maximum number of edges incident with v, that have distinct colors. In this paper, we prove that if G is an edge-colored triangle-free graph of order n ≥?9 and ${d^c(v) \geq \frac{(3-\sqrt{5})n}{2}+1}$ for each vertex v of G, G has a heterochromatic C 4. 相似文献
3.
William Kocay 《Graphs and Combinatorics》1992,8(3):259-276
LetV be a set ofn elements. The set of allk-subsets ofV is denoted
. Ak-hypergraph G consists of avertex-set V(G) and anedgeset
, wherek≥2. IfG is a 3-hypergraph, then the set of edges containing a given vertexvεV(G) define a graphG
v
. The graphs {G
v
νvεV(G)} aresubsumed byG. Each subsumed graphG
v
is a graph with vertex-setV(G) − v. They can form the set of vertex-deleted subgraphs of a graphH, that is, eachG
v
≽H −v, whereV(H)=V(G). In this case,G is a hypergraphic reconstruction ofH. We show that certain families of self-complementary graphsH can be reconstructed in this way by a hypergraphG, and thatG can be extended to a hypergraphG
*, all of whose subsumed graphs are isomorphic toH, whereG andG
* are self-complementary hypergraphs. In particular, the Paley graphs can be reconstructed in this way.
This work was supported by an operating grant from the Natural Sciences and Engineering Research Council of Canada. 相似文献
4.
A graph G with p vertices and q edges, vertex set V(G) and edge set E(G), is said to be super vertex-graceful (in short SVG), if there exists a function pair (f, f
+) where f is a bijection from V(G) onto P, f
+ is a bijection from E(G) onto Q, f
+((u, v)) = f(u) + f(v) for any (u, v) ∈ E(G),
5.
The signed distance-k-domination number of a graph is a certain variant of the signed domination number. If v is a vertex of a graph G, the open k-neighborhood of v, denoted by N
k
(v), is the set N
k
(v) = {u: u ≠ v and d(u, v) ⩽ k}. N
k
[v] = N
k
(v) ⋃ {v} is the closed k-neighborhood of v. A function f: V → {−1, 1} is a signed distance-k-dominating function of G, if for every vertex
. The signed distance-k-domination number, denoted by γ
k,s
(G), is the minimum weight of a signed distance-k-dominating function on G. The values of γ
2,s
(G) are found for graphs with small diameter, paths, circuits. At the end it is proved that γ
2,s
(T) is not bounded from below in general for any tree T. 相似文献
6.
JieLU JinChengXIONG JianCHEN 《数学学报(英文版)》2004,20(3):415-422
Let G be a graph which contains exactly one simple closed curve. We prove that a continuous map f : G → G has zero topological entropy if and only if there exist at most k ≤ |(Edg(G) End(G) 3)/2] different odd numbers n1,...,nk such that Per(f) is contained in ∪i=1^k ∪j=0^∞ ni2^j, where Edg(G) is the number of edges of G and End(G) is the number of end points of G. 相似文献
7.
Krzysztof Cieplinski 《Czechoslovak Mathematical Journal》2005,55(4):1079-1088
Let
be a disjoint iteration group on the unit circle
, that is a family of homeomorphisms such that F
v1 ○ F
v2 = F
v1+v2 for v
1, v
2 ∈ V and each F
v
either is the identity mapping or has no fixed point ((V, +) is a 2-divisible nontrivial Abelian group). Denote by
the set of all cluster points of {F
v
(z), v ∈ V} for
. In this paper we give a general construction of disjoint iteration groups for which
. 相似文献
8.
Let G be a multigraph. The star number s(G) of G is the minimum number of stars needed to decompose the edges of G. The star arboricity sa(G) of G is the minimum number of star forests needed to decompose the edges of G. As usual λK
n
denote the λ-fold complete graph on n vertices (i.e., the multigraph on n vertices such that there are λ edges between every pair of vertices). In this paper, we prove that for n ⩾ 2
9.
Asaf Nachmias 《Geometric And Functional Analysis》2009,19(4):1171-1194
Let {G n } be a sequence of finite transitive graphs with vertex degree d = d(n) and |G n | = n. Denote by p t (v, v) the return probability after t steps of the non-backtracking random walk on G n . We show that if p t (v, v) has quasi-random properties, then critical bond-percolation on G n behaves as it would on a random graph. More precisely, if $\mathop {\rm {lim\, sup\,}} \limits_{n} n^{1/3} \sum\limits_{t = 1}^{n^{1/3}} {t{\bf p}^t(v,v) < \infty ,}$ then the size of the largest component in p-bond-percolation with ${p =\frac{1+O(n^{-1/3})}{d-1}}
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