Working of the GHS algorithm Can someone explain the working of the GHS algorithm using the graph given below. GHS is a distributed algorithm for finding the Minimum Spanning tree of a graph. The description of which can be found here https://en.wikipedia.org/wiki/Distributed_minimum_spanning_tree 

What I think is that the fragments(the nodes in a fragment are shown within curly braces) will be formed as follows:

Step 1: {1, 2}
        {5, 6} {3}  {4}

Step 2: {1, 2, 3, 4}
        {5, 6}

Step 3: {1, 2, 3, 4, 5, 6} //as 1 and 5 get connected.

But what my professor said is that 4 will become a part of the MST at the end. These are the steps that he told us.

Step 1: {1, 2}
{5,6}// this step is the same
{3}{4}

Step 2: {1, 2, 3}{5,6}{4}

Step 3: {1, 2, 3, 5, 6}{4}

Step 4: {1, 2, 3, 4, 5, 6}

Can you please tell me which version is correct? 
The graph ->
Indeed.

Let the fragment at a particular stage be :
{1,2},{5,6},{3},{4}.

Now the fragment {1,2} will connect with the least weight outgoing edge which is 1-3 and fragment {5,6} will connect with the least weight outgoing edge which is 1-5 to create the fragment {1,2,3,5,6} and {4} and finally it connects to {4} with edge {2-4}.

Hope this helped.