The reconstruction of maximal planar graphs II. Reconstruction

In the first paper [3], the author, together with Fiorini, has shown that maximal planar graphs are recognizable from their decks of vertex-deleted subraphs. The aim of this paper is to show that such graphs are reconstructible.     

The reconstruction of maximal planar graphs. I. Recognition

The object of this paper is to show that every maximal planar graph is recognizable from its family of vertex-deleted subgraphs.     

The star-chromatic number of planar graphs

The star-chromatic number of a graph, a parameter introduced by Vince, is a natural generalization of the chromatic number of a graph. Here we construct planar graphs with star-chromatic number r, where r is any rational number between 2 and 3, partially answering a question of Vince. © 1997 John Wiley & Sons, Inc.     

Spanning maximal planar subgraphs of random graphs

We study the threshold for the existence of a spanning maximal planar subgraph in the random graph G_{n, p} . We show that it is very near p = 1/n^? We also discuss the threshold for the existence of a spanning maximal outerplanar subgraph. This is very near p = 1/n^½.     

On the connectivity of maximal planar graphs

Let d₁ ? d₂ ? … ? d_p be the vertex degrees of a maximal planar graph G. Etourneau has shown that if d₁ ? 6 and d_p = 5, then G is 5-connected. We generalize Etourneau's result by giving sufficient conditions in terms of the vertex degrees for G to be d_p -connected.     

Two trees in maximal planar bipartite graphs

It is proven that each maximal planar bipartite graph is decomposable into two trees. © 1993 John Wiley & Sons, Inc.     

The number of maximal independent sets in connected graphs

Generalizing a theorem of Moon and Moser, we determine the maximum number of maximal independent sets in a connected graph on n vertices for n sufficiently large, e.g., n > 50.     

Gdk图的平面性和平面图的色数

利用欧拉公式研究了Gdk图的平面性,获得了一个重要定理,并由此得到了关于平面图色数的一个结论.     

Gk^d图的平面性和平面图的色数

利用欧拉公式研究了Gdk图的平面性,获得了一个重要定理,并由此得到了关于平面图色数的一个结论.     

Degree-associated reconstruction number of graphs

A card of a graph G is a subgraph formed by deleting one vertex. The Reconstruction Conjecture states that each graph with at least three vertices is determined by its multiset of cards. A dacard specifies the degree of the deleted vertex along with the card. The degree-associated reconstruction number drn(G) is the minimum number of dacards that determine G. We show that drn(G)=2 for almost all graphs and determine when drn(G)=1. For k-regular n-vertex graphs, drn(G)≤min{k+2,n−k+1}. For vertex-transitive graphs (not complete or edgeless), we show that drn(G)≥3, give a sufficient condition for equality, and construct examples with large drn. Our most difficult result is that drn(G)=2 for all caterpillars except stars and one 6-vertex example. We conjecture that drn(G)≤2 for all but finitely many trees.     

On the tightness conditions for maximal planar graphs

We characterize the tight structure of a vertex-accumulation-free maximal planar graph with no separating triangles. Together with the result of Halin who gave an equivalent form for such graphs, this yields that a tight structure always exists in every 4-connected maximal planar graph with one end.     

A class of planar four-colorable graphs

A sufficient condition is given for a planar graph to be 4-colorable. This condition is in terms of the sums of the degrees of a subset of the vertex set of the graph.     

Rainbow number of matchings in planar graphs

The rainbow number$rb(G,H)$ for the graph $H$ in $G$ is defined to be the minimum integer $c$ such that any $c$-edge-coloring of $G$ contains a rainbow $H$. As one of the most important structures in graphs, the rainbow number of matchings has drawn much attention and has been extensively studied. Jendrol et al. initiated the rainbow number of matchings in planar graphs and they obtained bounds for the rainbow number of the matching $k{K}_2$ in the plane triangulations, where the gap between the lower and upper bounds is $O\left(k^3\right)$. In this paper, we show that the rainbow number of the matching $k{K}_2$ in maximal outerplanar graphs of order $n$ is $n+O\left(k\right)$. Using this technique, we show that the rainbow number of the matching $k{K}_2$ in some subfamilies of plane triangulations of order $n$ is $2n+O\left(k\right)$. The gaps between our lower and upper bounds are only $O\left(k\right)$.     

CHROMATIC NUMBER OF SQUARE OF MAXIMAL OUTERPLANAR GRAPHS

Let x（G^2） denote the chromatic number of the square of a maximal outerplanar graph G and Q denote a maximal outerplanar graph obtained by adding three chords y1 y3, y3y5, y5y1 to a 6-cycle y1y2…y6y1. In this paper, it is proved that △ ＋ 1 ≤ x（G^2） ≤△ ＋ 2, and x（G^2） = A ＋ 2 if and only if G is Q, where A represents the maximum degree of G.     

One-way infinite hamiltonian paths in infinite maximal planar graphs

A one-way infinite Hamiltonian path is constructed in an infinite 4-connected VAP-free maximal planar graph containing one or two vertices of infinite degree. Combining this result and that of R. HALIN who investigated the structure of such graphs, we conclude that such a path always exists in every infinite 4-connected maximal planar graph with exactly one end, which is an extension of H. WHITNEY'S theorem to infinite graphs.     

The maximum number of maximal independent sets in unicyclic connected graphs

In this paper, we determine the maximum number of maximal independent sets in a unicyclic connected graph. We also find a class of graphs achieving this maximum value.     

Remarks on the bondage number of planar graphs

The bondage number b(G) of a nonempty graph G is the cardinality of a smallest set of edges whose removal from G results in a graph with domination number greater than the domination number γ(G) of G. In 1998, J.E. Dunbar, T.W. Haynes, U. Teschner, and L. Volkmann posed the conjecture b(G)Δ(G)+1 for every nontrivial connected planar graph G. Two years later, L. Kang and J. Yuan proved b(G)8 for every connected planar graph G, and therefore, they confirmed the conjecture for Δ(G)7. In this paper we show that this conjecture is valid for all connected planar graphs of girth g(G)4 and maximum degree Δ(G)5 as well as for all not 3-regular graphs of girth g(G)5. Some further related results and open problems are also presented.