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67
Voted
DM
2006
14 years 9 months ago
2006
For an integer n 3, a rank-n matroid is called an n-spike if it consists of n three-point lines through a common point such that, for all k {1, 2, . . . , n - 1}, the union of e...
56
Voted
DM
2006
14 years 9 months ago
2006
We give an algorithmic characterisation of finite cop-win digraphs. The case of k > 1 cops and k l 1 robbers is then reduced to the one cop case. Similar characterisations are ...
DM
2006
14 years 9 months ago
2006
For a set X of vertices of a graph fulfilling local connectedness conditions the existence of a cycle containing X is proved. AMS classification: 05C38, 05C45, 05C35
DM
2006
14 years 9 months ago
2006
This paper shows that the number of sign patterns of totally non-zero symmetric n-by-n matrices, up to conjugation by monomial matrices and negation, is equal to the number of unl...
71
Voted
DM
2006
14 years 9 months ago
2006
Let G be a connected, locally connected, claw-free graph of order n and x, y be two vertices of G. In this paper, we prove that if for any 2-cut S of G, S {x, y} = , then each (x...