Hi,

Please help me to solve following problems

Let *G *= (*V; E;w*) be a weighted undirected graph whose edges are colored
either

red or green. That is *E *= *Er [ Eg *and *Er \ Eg *= *;*, where *Er *are
the red edges

and *Eg *are the green edges. Assume that all edge weights are distinct (so
that the

minimum spanning tree is unique). Also assume that there is at least one
green edge.

Suppose that the minimum spanning tree, *T*0, consists entirely of red
edges. Let *T*1 be

the minimum-cost tree among the spanning trees that have exactly one green
edge.

(a) Show, by giving an example, that *T*1 does not necessarily include the
lowset-cost

green edge.

(b) Prove that *T*1 can be obtained from *T*0 by swapping a red edge for a
green

edge. That is, there exists a green edge (*u; v*) and a red edge (*x; y*) such
that *T*1 =
*
T*0 *[ f*(*u; v*)*g ยก f*(*x; y*)*g*.


Thanks

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