On a condition for obtaining an explicit solution of optimum requirement spanning tree

The optimum requirement spanning tree (ORST) studied by Hu is known to be obtained by the Gomory–Hu algorithm when the degrees of vertices are not restricted. We consider a problem to find an ORST with maximum-degree constraints and suggest a particular spanning tree T* as a candidate for the solution to the problem. Further, we show a condition under which the tree T* is an explicit solution to the problem.