منابع مشابه
The Induced Subgraph Order on Unlabelled Graphs
A differential poset is a partially ordered set with raising and lowering operators U and D which satisfy the commutation relation DU−UD = rI for some constant r. This notion may be generalized to deal with the case in which there exist sequences of constants {qn}n≥0 and {rn}n≥0 such that for any poset element x of rank n, DU(x) = qnUD(x)+rnx. Here, we introduce natural raising and lowering ope...
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Let $G$ be a graph with vertex set $V(G)$ and edge set $E(G)$, a vertex labeling $f : V(G)rightarrow mathbb{Z}_2$ induces an edge labeling $ f^{+} : E(G)rightarrow mathbb{Z}_2$ defined by $f^{+}(xy) = f(x) + f(y)$, for each edge $ xyin E(G)$. For each $i in mathbb{Z}_2$, let $ v_{f}(i)=|{u in V(G) : f(u) = i}|$ and $e_{f^+}(i)=|{xyin E(G) : f^{+}(xy) = i}|$. A vertex labeling $f$ of a graph $G...
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Let β(G) and Γ(G) be the independence number and the upper domination number of a graphG, respectively. A graph G is called Γ-perfect if β(H) = Γ(H), for every induced subgraph H of G. The class of Γ-perfect graphs generalizes such well-known classes of graphs as strongly perfect graphs, absorbantly perfect graphs, and circular arc graphs. In this article, we present a characterization of Γ-per...
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In this Letter, we consider the parameterized complexity of the following problem: Given a hereditary property P on digraphs, an input digraph D and a positive integer k, does D have an induced subdigraph on k vertices with property P? We completely characterize hereditary properties for which this induced subgraph problem is W [1]-complete for two classes of directed graphs: general directed g...
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ژورنال
عنوان ژورنال: Theory and Application of Graphs
سال: 2017
ISSN: 2470-9859
DOI: 10.20429/tag.2017.030201