, 
can be immeduately fathomed by Test 1 (1 < incumbent objective = 4).
This is achieved by checking the "Fathomed" box below the node "x2 = 0"
emanating from the "x1 = 0" node. The subproblem with , 
cannot be fathomed, so we next will branch from this node (by clicking
on this node) with the next variable 
as the branching variable to start Iteration 4.