MORE GRAPHS WHOSE ENERGY EXCEEDS THE NUMBER OF VERTICES
نویسندگان
چکیده مقاله:
The energy E(G) of a graph G is equal to the sum of the absolute values of the eigenvalues of G. Several classes of graphs are known that satisfy the condition E(G) > n , where n is the number of vertices. We now show that the same property holds for (i) biregular graphs of degree a b , with q quadrangles, if q<= abn/4 and 5<=a < b = 0 (iii) triregular graphs of degree 1, a, b that are quadrangle-free, whose average vertex degree exceeds a , that have not more than 12n/13 pendent vertices, if 5<= a < b<=((a - 1)^2)/2 .
منابع مشابه
Unicyclic radially-maximal graphs on the minimum number of vertices
We characterize unicyclic, non-selfcentric, radially-maximal graphs on the minimum number of vertices. Such graphs must have radius r ≥ 5, and we prove that the number of these graphs is 1 48 r + O(r).
متن کاملThe bondage number of graphs: good and bad vertices
The domination number γ(G) of a graph G is the minimum number of vertices in a set D such that every vertex of the graph is either in D or is adjacent to a member of D. Any dominating set D of a graph G with |D| = γ(G) is called a γ-set of G. A vertex x of a graph G is called: (i) γ-good if x belongs to some γ-set and (ii) γ-bad if x belongs to no γ-set. The bondage number b(G) of a nonempty gr...
متن کاملAll Connected Graphs with Maximum Degree at Most 3 whose Energies are Equal to the Number of Vertices
The energy E(G) of a graph G is defined as the sum of the absolute values of its eigenvalues. Let S2 be the star of order 2 (or K2) and Q be the graph obtained from S2 by attaching two pendent edges to each of the end vertices of S2. Majstorović et al. conjectured that S2, Q and the complete bipartite graphs K2,2 and K3,3 are the only 4 connected graphs with maximum degree ∆ ≤ 3 whose energies ...
متن کاملOn the fixed number of graphs
A set of vertices $S$ of a graph $G$ is called a fixing set of $G$, if only the trivial automorphism of $G$ fixes every vertex in $S$. The fixing number of a graph is the smallest cardinality of a fixing set. The fixed number of a graph $G$ is the minimum $k$, such that every $k$-set of vertices of $G$ is a fixing set of $G$. A graph $G$ is called a $k$-fixed graph, if its fix...
متن کاملOn the saturation number of graphs
Let $G=(V,E)$ be a simple connected graph. A matching $M$ in a graph $G$ is a collection of edges of $G$ such that no two edges from $M$ share a vertex. A matching $M$ is maximal if it cannot be extended to a larger matching in $G$. The cardinality of any smallest maximal matching in $G$ is the saturation number of $G$ and is denoted by $s(G)$. In this paper we study the saturation numbe...
متن کاملOn the super domination number of graphs
The open neighborhood of a vertex $v$ of a graph $G$ is the set $N(v)$ consisting of all vertices adjacent to $v$ in $G$. For $Dsubseteq V(G)$, we define $overline{D}=V(G)setminus D$. A set $Dsubseteq V(G)$ is called a super dominating set of $G$ if for every vertex $uin overline{D}$, there exists $vin D$ such that $N(v)cap overline{D}={u}$. The super domination number of $G$ is the minimum car...
متن کاملمنابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ذخیره در منابع من قبلا به منابع من ذحیره شده{@ msg_add @}
عنوان ژورنال
دوره 2 شماره None
صفحات 57- 62
تاریخ انتشار 2007-11
با دنبال کردن یک ژورنال هنگامی که شماره جدید این ژورنال منتشر می شود به شما از طریق ایمیل اطلاع داده می شود.
میزبانی شده توسط پلتفرم ابری doprax.com
copyright © 2015-2023