✦ LIBER ✦

A Characterization of Half-Dual Polar Graphs

✍ Scribed by Tung-Shan Fu

Publisher: Elsevier Science
Year: 1999
Tongue: English
Weight: 82 KB
Volume: 20
Category: Article
ISSN: 0195-6698
DOI: 10.1006/eujc.1998.0270

No coin nor oath required. For personal study only.

✦ Synopsis

The half-dual polar graphs are characterized among distance-regular graphs with all singular lines of constant size of at least three by their parameters and some extra conditions.

📜 SIMILAR VOLUMES

A characterization of partially dual gra

A characterization of partially dual graphs

✍ Iain Moffatt 📂 Article 📅 2010 🏛 John Wiley and Sons 🌐 English ⚖ 332 KB

In this article, we extend the recently introduced concept of partially dual ribbon graphs to graphs. We then go on to characterize partial duality of graphs in terms of bijections between edge sets of corresponding graphs. This result generalizes a well-known result of J. Edmonds in which natural d

Antidesigns and regularity of partial sp

Antidesigns and regularity of partial spreads in dual polar graphs

✍ Frédéric Vanhove 📂 Article 📅 2010 🏛 John Wiley and Sons 🌐 English ⚖ 149 KB

We give several examples of designs and antidesigns in classical finite polar spaces. These types of subsets of maximal totally isotropic subspaces generalize the dualization of the concepts of m-ovoids and tight sets of points in generalized quadrangles. We also consider regularity of partial sprea

A characterization of Seymour graphs

✍ Ageev, A. A.; Kostochka, A. V.; Szigeti, Z. 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 105 KB 👁 1 views

A connected undirected graph G is called a Seymour graph if the maximum number of edge disjoint T -cuts is equal to the cardinality of a minimum T -join for every even subset T of V (G). Several families of graphs have been shown to be subfamilies of Seymour graphs (Seymour

A characterization of ptolemaic graphs

✍ Edward Howorka 📂 Article 📅 1981 🏛 John Wiley and Sons 🌐 English ⚖ 466 KB

A connected graph G is ptolernaic provided that for each four vertices u,, 1 5 i 5 4, of G, the six distances d, =dG (u,ui), i f j satisfy the inequality d,2d34 5 d,3d24 + d,4d23 (shown by Ptolemy t o hold in Euclidean spaces). Ptolemaic graphs were first investigated by Chartrand and Kay, who showe

A characterization of ?-outerplanar grap

A characterization of ?-outerplanar graphs

✍ Wargo, Lawrence 📂 Article 📅 1996 🏛 John Wiley and Sons 🌐 English ⚖ 528 KB

Chartrand and Harary have shown that if G is a non-outerplanar graph such that, for every edge e, both the deletion G \ e and the contraction G/e of e from G are outerplanar, then G is isomorphic to K4 or K2,3. An a-outerplanar graph is a graph which is not outerplanar such that, for some edge a , b

A characterization of radius-critical gr

A characterization of radius-critical graphs

✍ Siemion Fajtlowicz 📂 Article 📅 1988 🏛 John Wiley and Sons 🌐 English ⚖ 201 KB

A graph G is radius-critical if every proper induced connected subgraph of G has radius strictly smaller than the original graph. Our main purpose is to characterize all such graphs. 1. By a graph we shall mean here a finite, simple, undirected graph. For a connected graph the distance between two