Math Is Fun Forum

jim1

Member

Registered: 2007-04-27

Posts: 4

Discrete Math

1. Determine if the directed graph is a rooted tree. 

2. Draw the rooted tree in the usual way, with the root at the top and without the arrowheads.

I am trying to figure this one out. I am lost HELP!!!

Please explain your answer.

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: Discrete Math

1.  What is the definition of a rooted tree?  Does the graph fit the definition?  This should be really straightforward.

2. If you know that the graph is a rooted tree, then you must know that it has a root.  If you know it has a root, then you must know where this root is.  Start with the root, then follow the directed edges down to each child.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: Discrete Math

The ancestor has three children, two of them have a grand-children each and the rest one has none.

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X'(y-Xβ)=0