Find all possible spanning trees for the graph SolutionEdge
     Find all possible spanning trees for the graph   
  
  Solution
Edge bc has to be present in all such spanning trees as vertex c is incident only on this edge
Case 1: ab is included in spanning tree
Case 1.1 bd is present. Then the tree is consisting of these three edges
{bc,bd,ba}
Case 1.2 ad is present. Then the tree is consisting of these three edges
{bc,ba,ad}
Case 2: ab is not present
Then spanning tree is: {bc,bd,ad}

