| J. Edmonds, "Edge-disjoint branchings, combinatorial algorithms," Combinatorial Algorithms, R. Rustin, ed., New York, Algorithmic Press, 1972. |
.... resulting subgraph is still connected (strongly connected) 2] An algorithm for communicating in a digraph D(V, A) can tolerate f faults if and only if each data element can be routed through at least f 1 node disjoint paths from its source to its destination [11] It has been proven by Edmonds [10] that every digraph possesses as many arc disjoint spanning trees rooted at any node as the arc connectivity of the digraph. Here, for a digraph D = V, A) arc connectivity represents the minimum number of elements in an arc set A such that D = V, A A ) is not a strongly connected digraph. ....
J. Edmonds, "Edge-disjoint branchings, combinatorial algorithms," Combinatorial Algorithms, R. Rustin, ed., New York, Algorithmic Press, 1972.
....are minimal with respect to edge deletion. The main observation is that such digraphs are precisely those in which (a) the in degree of every node v 6= s is precisely k and (b) the underlining undirected graph is the union of k disjoint spanning trees. The equivalence may be proved by Edmonds [1973] disjoint arborescence theorem) By this equivalent formulation the problem is to find a minimum cost common basis of two matroids M 1 and M 2 defined on the edge set of D. Here M 1 is a partition matroid in which a set is independent if contains at most k edges entering any node v 6= s. M 2 is ....
....k connectivity augmentation problem also has a solution. Unfortunately, at present, it is not known if the problem is NP complete or it is perhaps in co NP NP or even in P. 17 For general k, F. Harary [1962] found the solution when the starting graph has n nodes but no edges. Wang and Kleitman [1973] determined a necessary and sufficient condition for the existence of a k connected graph with specified degree sequence. For general starting graphs, solutions are known only for small k. When k = 1 the problem is obvious. Plesnik [1976] and Eswaran and Tarjan [1976] proved a min max formula for ....
J. Edmonds, Edge-disjoint branchings in: Combinatorial Algorithms (B. Rustin, ed.), Acad. Press, New York, (1973), 91-96.
.... we are given a subset T U Gamma z so that (X) k for every subset X U Gamma z; X T 6= Is it true that there are k disjoint arborescences so that each contains every element of T The answer is yes if T = U Gamma z (by Edmonds theorem) or if jT j = 1 (by Menger s theorem) But Lov asz [1973] found the the following example to show that such a statement is not true in general. Figure 2.1 Here k = 2, T consists of three nodes and there are no two disjoint arborescences both containing every element of T . Observe that (x) 1 ffi (x) 2 holds for the only node x not in T . In this ....
J. Edmonds, Edge-disjoint branchings in: Combinatorial Algorithms (B. Rustin, ed.), Acad. Press, New York, (1973), 91-96.
Online articles have much greater impact More about CiteSeer.IST Add search form to your site Submit documents Feedback
CiteSeer.IST - Copyright Penn State and NEC