The closure of a set A of vertices of an infinite graph G is defined as the set of vertices of G which cannot be finitely separated from A. A subset A of Y(G) is dispersed if it is finitely separated from any ray of G. It is shown that the closure of any dispersed set A of an infinite connected grap
Large k-preserving sets in infinite graphs
β Scribed by Andreas Huck; Frank Niedermeyer; Saharon Shelah
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 715 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
β¦ Synopsis
Abstract
Let K be a cardinal. If K Ο~0~, define K:= K. Otherwise, let K := K + 1. We prove a conjecture of Mader: Every infinite Kβconnected graph G = (V, E) contains a set S β V with |S| = |V| such that G/S is Kβconnected for all Sβ S.
π SIMILAR VOLUMES
While finite cop-win finite graphs possess a good structural characterization, none is known for infinite cop-win graphs. As evidence that such a characterization might not exist, we provide as large as possible classes of infinite graphs with finite cop number. More precisely, for each infinite car
## An automorphism of a graph X is called a translation of X if it fixes no finite non-empty set of vertices of X. It is shown that a group G of automorphisms of the connected graph X fixes a finite non-empty set of vertices or ends of X if and only if any two translations of X in G have a common
Hajnal, A. and N. Sauer, Cut-sets in infinite graphs and partial orders. Discrete Mathematics 117 (1993) 113-125. The set S c V(U) is a cut-set of the vertex v of a graph 9 if v is not adjacent to any vertex in S and, for every maximal clique C of Q, ({v} u S) n C # 0. S is a cut-set of the element